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, core.stdc.stdlib, std.datetime;

immutable long MOD = 10^^9 + 7;

void main() {
    auto s = readln.split.map!(to!int);
    auto N = s[0];
    auto M = s[1];
    auto X = s[2].to!long;

    long score(long c) {
        return powmod(X, c, MOD);
    }

    Tuple!(int, int, long)[] E;
    foreach (_; 0..M) {
        s = readln.split.map!(to!int);
        auto a = s[0] - 1;
        auto b = s[1] - 1;
        auto c = s[2].to!long;
        E ~= tuple(a, b, c);
    }
    E.sort!"a[2] < b[2]";

    auto uf = new UnionFind(N);
    auto G = new Tuple!(int, long)[][](N);

    foreach (e; E) {
        auto a = e[0];
        auto b = e[1];
        auto c = e[2];
        if (uf.find(a) == uf.find(b)) continue;
        uf.unite(a, b);
        G[a] ~= tuple(b, c);
        G[b] ~= tuple(a, c);
    }

    auto sub = new int[](N);
    void dfs1(int n, int p) {
        sub[n] = 1;
        foreach (e; G[n]) {
            auto m = e[0];
            if (m != p) {
                dfs1(m, n);
                sub[n] += sub[m];
            }
        }
    }
    dfs1(0, -1);

    auto dp = new long[](N);
    void dfs2(int n, int p) {
        foreach (e; G[n]) {
            auto m = e[0];
            auto c = e[1];
            if (m != p) {
                dfs2(m, n);
                dp[n] += dp[m] + sub[m] * score(c) % MOD;
                dp[n] %= MOD;
            }
        }
    }
    dfs2(0, -1);

    auto ans = new long[](N);
    void dfs3(int n, int p, long cp) {
        if (p == -1) {
            ans[n] = dp[n];
        } else {
            ans[n] = ans[p] - sub[n] * score(cp) % MOD + (N - sub[n]) * score(cp) % MOD;
            ans[n] = (ans[n] % MOD + MOD) % MOD;
        }
        foreach (e; G[n]) {
            auto m = e[0];
            auto c = e[1];
            if (m != p) dfs3(m, n, c);
        }
    }
    dfs3(0, -1, 0);

    long ansans = 0;
    foreach (a; ans) (ansans += a) %= MOD;
    ansans = ansans * powmod(2, MOD-2, MOD) % MOD;

    ansans.writeln;
}

class UnionFind {
    import std.algorithm : swap;

    int n;
    int[] table;

    this(int n) {
        this.n = n;
        table = new int[](n);
        table[] = -1;
    }

    int find(int x) {
        return table[x] < 0 ? x : (table[x] = find(table[x]));
    }

    void unite(int x, int y) {
        x = find(x);
        y = find(y);
        if (x == y) return;
        if (table[x] > table[y]) swap(x, y);
        table[x] += table[y];
        table[y] = x;
    }

    bool same(int x, int y) {
        return find(x) == find(y);
    }
}

long powmod(long a, long x, long m) {
    long ret = 1;
    while (x) {
        if (x % 2) ret = ret * a % m;
        a = a * a % m;
        x /= 2;
    }
    return ret;
}