import std.stdio, std.string, std.conv;
import std.range, std.algorithm, std.array, std.typecons, std.container;
import std.math, std.numeric, core.bitop;

enum inf = 1_001_001_001;
enum inf6 = 1_001_001_001_001_001_001L;
enum mod = 1_000_000_007L;

void main() {
    int N, K;
    scan(N, K);

    if (K == 1) {
        writeln(N == 1 ? 1 : 0);
        return;
    }

    auto adj = new int[][](N, 0);

    foreach (i ; 0 .. N - 1) {
        int ai, bi;
        scan(ai, bi);
        ai--, bi--;
        adj[ai] ~= bi;
        adj[bi] ~= ai;
    }

    long dfs(int v, int p, int dep) {
        long res = 1;
        long t = dep > 0 ? K - 2 : K - 1;

        foreach (u ; adj[v]) if (u != p) {
            res *= t * dfs(u, v, dep + 1) % mod;
            res %= mod;
            t--;
            if (t < 0) t = 0;
        }

        debug {
            writefln("v: %d, res: %d", v, res);
        }

        return res;
    }

    auto ans = dfs(0, -1, 0) * K % mod;
    writeln(ans);
}








void scan(T...)(ref T args) {
    import std.stdio : readln;
    import std.algorithm : splitter;
    import std.conv : to;
    import std.range.primitives;

    auto line = readln().splitter();
    foreach (ref arg; args) {
        arg = line.front.to!(typeof(arg));
        line.popFront();
    }
    assert(line.empty);
}

void fillAll(R, T)(ref R arr, T value) {
    static if (is(typeof(arr[] = value))) {
        arr[] = value;
    }
    else {
        foreach (ref e; arr) {
            fillAll(e, value);
        }
    }
}

bool chmin(T, U...)(ref T x, U args) {
    bool isChanged;

    foreach (arg; args) {
        if (x > arg) {
            x = arg;
            isChanged = true;
        }
    }

    return isChanged;
}

bool chmax(T, U...)(ref T x, U args) {
    bool isChanged;

    foreach (arg; args) {
        if (x < arg) {
            x = arg;
            isChanged = true;
        }
    }

    return isChanged;
}
