import std.conv, std.functional, std.range, std.stdio, std.string; import std.algorithm, std.array, std.bigint, std.bitmanip, std.complex, std.container, std.math, std.mathspecial, std.numeric, std.regex, std.typecons; import core.bitop; class EOFException : Throwable { this() { super("EOF"); } } string[] tokens; string readToken() { for (; tokens.empty; ) { if (stdin.eof) { throw new EOFException; } tokens = readln.split; } auto token = tokens.front; tokens.popFront; return token; } int readInt() { return readToken.to!int; } long readLong() { return readToken.to!long; } real readReal() { return readToken.to!real; } bool chmin(T)(ref T t, in T f) { if (t > f) { t = f; return true; } else { return false; } } bool chmax(T)(ref T t, in T f) { if (t < f) { t = f; return true; } else { return false; } } int binarySearch(alias pred, T)(in T[] as) { int lo = -1, hi = cast(int)(as.length); for (; lo + 1 < hi; ) { const mid = (lo + hi) >> 1; (unaryFun!pred(as[mid]) ? hi : lo) = mid; } return hi; } int lowerBound(T)(in T[] as, T val) { return as.binarySearch!(a => (a >= val)); } int upperBound(T)(in T[] as, T val) { return as.binarySearch!(a => (a > val)); } int N, K; int[] A, B; int[][] G; int[] dep; void dfs(int u, int p) { dep[u] = (p == -1) ? 0 : (dep[p] + 1); foreach (i; G[u]) { const v = A[i] ^ B[i] ^ u; if (v != p) { dfs(v, u); } } } void main() { try { for (; ; ) { N = readInt(); K = readInt(); A = new int[N - 1]; B = new int[N - 1]; foreach (i; 0 .. N - 1) { A[i] = readInt() - 1; B[i] = readInt() - 1; } G = new int[][N]; foreach (i; 0 .. N - 1) { G[A[i]] ~= i; G[B[i]] ~= i; } dep = new int[N]; dfs(0, -1); long ans; if (K <= N) { /* auto ds = dep.dup; ds.sort; ans = ds[0 .. K].sum; */ ans = K - 1; } else { ans = -1; } writeln(ans); } } catch (EOFException e) { } }