import std.stdio, std.array, std.string, std.conv, std.algorithm; import std.typecons, std.range, std.random, std.math, std.container; import std.numeric, std.bigint, core.bitop; void main() { immutable long MOD = 10^^9 + 7; auto s = readln.split.map!(to!int); auto N = s[0]; auto K = s[1]; auto edges = new int[][](N); foreach (i; 0..N-1) { s = readln.split.map!(to!int); edges[s[0]] ~= s[1]; edges[s[1]] ~= s[0]; } auto children = new int[](N); auto dp = new long[][](N, N+2); foreach (i; 0..N) fill(dp[i], 0); int dfs1(int n, int prev) { children[n] = 1; foreach (m; edges[n]) if (m != prev) children[n] += dfs1(m, n); return children[n]; } void dfs2(int n, int prev) { foreach (m; edges[n]) if (m != prev) dfs2(m, n); dp[n][children[n]] = 1; if (children[n] == 1) return; foreach (m; edges[n]) { if (m == prev) continue; auto tmp = new long[](children[n]+1); fill(tmp, 0); foreach (i; 0..children[n]) { foreach (j; 0..children[m]+1) { if (i + j > children[n]) break; tmp[i+j] += dp[n][i] * dp[m][j]; } } foreach (i; 0..children[n]+1) dp[n][i] += tmp[i]; foreach (i; 0..children[m]+1) dp[n][i] += dp[m][i]; } } dfs1(0, -1); dfs2(0, -1); //dp.each!writeln; dp[0][K].writeln; }