import java.util.Scanner

val isSafelyIncreasing = { offset: Int -> offset in 1..3 }

val isSafelyDecreasing = { offset: Int -> offset in (-3)..(-1) }

fun isSafeRoute(levels: List<Int>): Boolean {
    val levelOffsets = levels.foldIndexed(ArrayList<Int>()) { index, acc, i ->
        if (index > 0) {
            acc.add(i - levels[index - 1])
        }
        acc
    }

    return levelOffsets.all(isSafelyIncreasing) || levelOffsets.all(isSafelyDecreasing)
}

val scanner = Scanner(System.`in`)

var safeCount = 0
while (scanner.hasNextInt()) {
    val line = scanner.nextLine()

    val numbers = line.split(" ").map { it.toInt() }

    if (isSafeRoute(numbers)) {
        safeCount++
    }
}

println(safeCount)