import kotlin.math.max

fun main(arr:Array<String>) {
    val columnCount = readLine()!!.toInt()
    val barCount = readLine()!!.toInt()
    val barMap = (0 until barCount).map { readLine()!!.split(" ").map { it.toInt() - 1 } }

    val moveTo = (0 until columnCount).map {
        getGoal(it, barMap)
    }

    var numList = (0 until columnCount).map { it }
    for(i in (1..10000000)) {
        var tmp = numList.withIndex().sortedBy { moveTo[it.index] }.map { it.value }
        numList = tmp
        if(numList.withIndex().all { it.index == it.value }) {
            println(i)
            return
        }
    }

}

fun getGoal(column:Int, barMap:List<List<Int>>):Int {
    var current = column
    for((f,t) in barMap) {
        if(f == current) {
            current = t
        } else if(current == t) {
            current = f
        }
    }
    return current
}