diff --git a/03-a.kts b/03-a.kts
new file mode 100644
index 0000000..8451fe7
--- /dev/null
+++ b/03-a.kts
@@ -0,0 +1,13 @@
+import java.util.Scanner
+import java.util.regex.Pattern
+
+val pattern: Pattern = Pattern.compile("mul\\([0-9]+,[0-9]+\\)")
+val scanner = Scanner(System.`in`)
+
+var sum = 0
+while (true) {
+    val next: String = scanner.findWithinHorizon(pattern, 0) ?: break
+
+    sum += next.replace("mul(", "").replace(")", "").split(",").map { it.toInt() }.let { (a, b) -> a*b }
+}
+println(sum)
\ No newline at end of file
diff --git a/03-b.kts b/03-b.kts
new file mode 100644
index 0000000..ff03734
--- /dev/null
+++ b/03-b.kts
@@ -0,0 +1,21 @@
+import java.util.Scanner
+import java.util.regex.Pattern
+
+val pattern: Pattern = Pattern.compile("mul\\([0-9]+,[0-9]+\\)|do\\(\\)|don't\\(\\)")
+
+val scanner = Scanner(System.`in`)
+
+var sum = 0
+var enabled = true
+while (true) {
+    val next: String = scanner.findWithinHorizon(pattern, 0) ?: break
+
+    when (next) {
+        "do()" -> enabled = true
+        "don't()" -> enabled = false
+        else -> if (enabled) {
+            sum += next.replace("mul(", "").replace(")", "").split(",").map { it.toInt() }.let { (a, b) -> a*b }
+        }
+    }
+}
+println(sum)
\ No newline at end of file
diff --git a/04-a.kts b/04-a.kts
new file mode 100644
index 0000000..672ec67
--- /dev/null
+++ b/04-a.kts
@@ -0,0 +1,59 @@
+import java.util.Scanner
+
+val scanner = Scanner(System.`in`)
+
+val matrix = ArrayList<CharArray>()
+
+while (scanner.hasNextLine()) {
+    val line = scanner.nextLine()
+    matrix.add(line.toCharArray())
+}
+
+var count = 0
+
+matrix.forEachIndexed { row, line ->
+    line.forEachIndexed { col, char ->
+        count += searchFrom(matrix, row, col)
+    }
+}
+println(count)
+
+fun searchFrom(matrix: ArrayList<CharArray>, row: Int, col: Int): Int {
+    return (if (safeCheckMatrix(matrix, row, col, 'X')
+        && safeCheckMatrix(matrix, row, col + 1, 'M')
+        && safeCheckMatrix(matrix, row, col + 2, 'A')
+        && safeCheckMatrix(matrix, row, col + 3, 'S')
+    ) 1 else 0) + (if (safeCheckMatrix(matrix, row, col, 'X')
+        && safeCheckMatrix(matrix, row, col - 1, 'M')
+        && safeCheckMatrix(matrix, row, col - 2, 'A')
+        && safeCheckMatrix(matrix, row, col - 3, 'S')
+    ) 1 else 0) + (if (safeCheckMatrix(matrix, row, col, 'X')
+        && safeCheckMatrix(matrix, row + 1, col + 1, 'M')
+        && safeCheckMatrix(matrix, row + 2, col + 2, 'A')
+        && safeCheckMatrix(matrix, row + 3, col + 3, 'S')
+    ) 1 else 0) + (if (safeCheckMatrix(matrix, row, col, 'X')
+        && safeCheckMatrix(matrix, row + 1, col, 'M')
+        && safeCheckMatrix(matrix, row + 2, col, 'A')
+        && safeCheckMatrix(matrix, row + 3, col, 'S')
+    ) 1 else 0) + (if (safeCheckMatrix(matrix, row, col, 'X')
+        && safeCheckMatrix(matrix, row + 1, col - 1, 'M')
+        && safeCheckMatrix(matrix, row + 2, col - 2, 'A')
+        && safeCheckMatrix(matrix, row + 3, col - 3, 'S')
+    ) 1 else 0) + (if (safeCheckMatrix(matrix, row, col, 'X')
+        && safeCheckMatrix(matrix, row - 1, col + 1, 'M')
+        && safeCheckMatrix(matrix, row - 2, col + 2, 'A')
+        && safeCheckMatrix(matrix, row - 3, col + 3, 'S')
+    ) 1 else 0) + (if (safeCheckMatrix(matrix, row, col, 'X')
+        && safeCheckMatrix(matrix, row - 1, col, 'M')
+        && safeCheckMatrix(matrix, row - 2, col, 'A')
+        && safeCheckMatrix(matrix, row - 3, col, 'S')
+    ) 1 else 0) + (if (safeCheckMatrix(matrix, row, col, 'X')
+        && safeCheckMatrix(matrix, row - 1, col - 1, 'M')
+        && safeCheckMatrix(matrix, row - 2, col - 2, 'A')
+        && safeCheckMatrix(matrix, row - 3, col - 3, 'S')
+    ) 1 else 0)
+}
+
+fun safeCheckMatrix(matrix: ArrayList<CharArray>, row: Int, col: Int, target: Char): Boolean {
+    return row in matrix.indices && col in matrix[row].indices && matrix[row][col] == target
+}
\ No newline at end of file
diff --git a/04-b.kts b/04-b.kts
new file mode 100644
index 0000000..a8cfe20
--- /dev/null
+++ b/04-b.kts
@@ -0,0 +1,47 @@
+import java.util.*
+
+val scanner = Scanner(System.`in`)
+
+val matrix = ArrayList<CharArray>()
+
+while (scanner.hasNextLine()) {
+    val line = scanner.nextLine()
+    matrix.add(line.toCharArray())
+}
+
+var count = 0
+
+matrix.forEachIndexed { row, line ->
+    line.forEachIndexed { col, char ->
+        count += searchFrom(matrix, row, col)
+    }
+}
+println(count)
+
+fun searchFrom(matrix: ArrayList<CharArray>, row: Int, col: Int): Int {
+    return (if (safeCheckMatrix(matrix, row, col, 'A') &&
+        safeCheckMatrix(matrix, row - 1, col - 1, 'M') &&
+        safeCheckMatrix(matrix, row - 1, col + 1, 'M') &&
+        safeCheckMatrix(matrix, row + 1, col - 1, 'S') &&
+        safeCheckMatrix(matrix, row + 1, col + 1, 'S')
+    ) 1 else 0) + (if (safeCheckMatrix(matrix, row, col, 'A') &&
+        safeCheckMatrix(matrix, row + 1, col - 1, 'M') &&
+        safeCheckMatrix(matrix, row + 1, col + 1, 'M') &&
+        safeCheckMatrix(matrix, row - 1, col - 1, 'S') &&
+        safeCheckMatrix(matrix, row - 1, col + 1, 'S')
+    ) 1 else 0) + (if (safeCheckMatrix(matrix, row, col, 'A') &&
+        safeCheckMatrix(matrix, row - 1, col - 1, 'M') &&
+        safeCheckMatrix(matrix, row + 1, col - 1, 'M') &&
+        safeCheckMatrix(matrix, row - 1, col + 1, 'S') &&
+        safeCheckMatrix(matrix, row + 1, col + 1, 'S')
+    ) 1 else 0) + (if (safeCheckMatrix(matrix, row, col, 'A') &&
+        safeCheckMatrix(matrix, row - 1, col + 1, 'M') &&
+        safeCheckMatrix(matrix, row + 1, col + 1, 'M') &&
+        safeCheckMatrix(matrix, row - 1, col - 1, 'S') &&
+        safeCheckMatrix(matrix, row + 1, col - 1, 'S')
+    ) 1 else 0)
+}
+
+fun safeCheckMatrix(matrix: ArrayList<CharArray>, row: Int, col: Int, target: Char): Boolean {
+    return row in matrix.indices && col in matrix[row].indices && matrix[row][col] == target
+}
\ No newline at end of file
diff --git a/05-a.kts b/05-a.kts
new file mode 100644
index 0000000..8c88f89
--- /dev/null
+++ b/05-a.kts
@@ -0,0 +1,39 @@
+import java.util.Scanner
+
+val scanner = Scanner(System.`in`)
+
+val rules = HashMap<Int, MutableSet<Int>>()
+
+while (scanner.hasNextLine()) {
+    val line = scanner.nextLine()
+    if (line == "") {
+        break;
+    }
+
+    val (before, after) = line.split("|").map(String::toInt)
+    if (!rules.contains(before)) {
+        rules[before] = HashSet<Int>()
+    }
+    rules[before]!!.add(after)
+}
+
+var sum = 0
+while (scanner.hasNextLine()) {
+    val line = scanner.nextLine()
+    val pages = line.split(",").map(String::toInt)
+
+    val result = pages.fold(Pair(HashSet<Int>(), true)) { (appeared, isSafe), page ->
+        val shouldBeAfter = rules[page]?.toSet() ?: emptySet()
+        val violateRule = appeared.intersect(shouldBeAfter)
+        val stillSafe = isSafe && violateRule.isEmpty()
+
+        appeared.add(page)
+        Pair(appeared, stillSafe)
+    }
+
+    if (result.second) {
+        val pagesArray = pages.toIntArray()
+        sum += pagesArray[pagesArray.size / 2]
+    }
+}
+println(sum)
\ No newline at end of file
diff --git a/05-b.kts b/05-b.kts
new file mode 100644
index 0000000..34e2db2
--- /dev/null
+++ b/05-b.kts
@@ -0,0 +1,31 @@
+import java.util.Scanner
+
+val scanner = Scanner(System.`in`)
+
+val rules = HashMap<Int, MutableSet<Int>>()
+
+while (scanner.hasNextLine()) {
+    val line = scanner.nextLine()
+    if (line == "") {
+        break;
+    }
+
+    val (before, after) = line.split("|").map(String::toInt)
+    if (!rules.contains(before)) {
+        rules[before] = HashSet<Int>()
+    }
+    rules[before]!!.add(after)
+}
+
+var sum = 0
+while (scanner.hasNextLine()) {
+    val line = scanner.nextLine()
+    val pages = line.split(",").map(String::toInt)
+    val fixed = pages.sortedWith { l, r -> if (l == r) 0 else if (rules[l]?.contains(r) == true) -1 else 1 }
+
+    if ("$pages" != "$fixed") {
+        val fixedArray = fixed.toIntArray()
+        sum += fixedArray[fixedArray.size / 2]
+    }
+}
+println(sum)
\ No newline at end of file