fun main(args: Array<String>) {
	val (n, k) = readLine()!!.split(" ").map(String::toInt)
	var a = Array(n, { 0 })
	var b = Array(n, { 0 })
	var g = Array<MutableList<Int>>(n, { mutableListOf() })

	for (i in 0 until n - 1) {
		val (x, y) = readLine()!!.split(" ").map(String::toInt)
		a[i] = x - 1
		b[i] = y - 1
		g[a[i]].add(i)
		g[b[i]].add(i)
	}

	if (n < k) {
		println(-1)
		return
	}
	
	var dist = Array(n, { if (it == 0) { 0L } else { -1L }})
	fun solve(now: Int, depth: Long) {
		dist[now] = depth
		for (id in g[now]) {
			val to = a[id] xor b[id] xor now
			if (dist[to] != -1L) continue

			solve(to, depth + 1)
		}
	}
	solve(0, 0)
	dist.sort()

	var ans: Long = 0
	for (i in 0 until k) ans += dist[i]
	println(ans)
}