#include <iostream>
#include <vector>
#include <algorithm>
#include <cmath>
#include <queue>
#include <string>
#include <map>
#include <set>
#include <stack>
#include <tuple>
#include <deque>
#include <array>
#include <numeric>
#include <bitset>
#include <iomanip>
#include <cassert>
#include <chrono>
#include <random>
#include <limits>
#include <iterator>
#include <functional>
#include <sstream>
#include <fstream>
#include <complex>
#include <cstring>
#include <unordered_map>
using namespace std;

using ll = long long;
using P = pair<int, int>;
constexpr int INF = 1001001001;
constexpr int mod = 1000000007;
// constexpr int mod = 998244353;

template<class T>
inline bool chmax(T& x, T y){
    if(x < y){
        x = y;
        return true;
    }
    return false;
}
template<class T>
inline bool chmin(T& x, T y){
    if(x > y){
        x = y;
        return true;
    }
    return false;
}

struct mint {
    int x;
    mint() : x(0) {}
    mint(int64_t y) : x(y >= 0 ? y % mod : (mod - (-y) % mod) % mod) {}
    mint& operator+=(const mint& p){
        if((x += p.x) >= mod)   x -= mod;
        return *this;
    }
    mint& operator-=(const mint& p){
        if((x -= p.x) < 0)  x += mod;
        return *this;
    }
    mint& operator*=(const mint& p){
        x = (int)(1LL * x * p.x % mod);
        return *this;
    }
    mint& operator/=(const mint& p){
        *this *= p.inverse();
        return *this;
    }
    mint operator-() const { return mint(-x); }
    mint operator+(const mint& p) const { return mint(*this) += p; }
    mint operator-(const mint& p) const { return mint(*this) -= p; }
    mint operator*(const mint& p) const { return mint(*this) *= p; }
    mint operator/(const mint& p) const { return mint(*this) /= p; }
    bool operator==(const mint& p) const { return x == p.x; }
    bool operator!=(const mint& p) const { return x != p.x; }
    mint pow(int64_t n) const {
        mint res = 1, mul = x;
        while(n > 0){
            if(n & 1)   res *= mul;
            mul *= mul;
            n >>= 1;
        }
        return res;
    }
    mint inverse() const { return pow(mod - 2); }
    friend ostream& operator<<(ostream& os, const mint& p){
        return os << p.x;
    }
    friend istream& operator>>(istream& is, mint& p){
        int64_t val;
        is >> val;
        p = mint(val);
        return is;
    }
};

struct UnionFind{
    int sz;     // vertex number
    vector<int> par;
    vector<int> rank;

    UnionFind(int n) : sz(n) {
        par.resize(sz);
        rank.assign(sz, 0);
        for(int i = 0; i < sz; ++i){
            par[i] = i;
        }
    }

    int find(int x){
        if(par[x] == x) return x;
        else    return par[x] = find(par[x]);
    }

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

    void unite(int x, int y){
        x = find(x), y = find(y);
        if(x == y)  return;
        if(rank[x] < rank[y])   par[x] = y;
        else{
            par[y] = x;
            if(rank[x] == rank[y])  ++rank[x];
        }
    }
};

int main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    int N, M, X;
    cin >> N >> M >> X;
    vector<tuple<int, int, int>> es(M);
    for(auto& [z, x, y] : es){
        cin >> x >> y >> z;
        --x, --y;
    }
    sort(es.begin(), es.end());

    vector<vector<pair<int, mint>>> graph(N);
    UnionFind uf(N);
    for(auto& [z, x, y] : es){
        if(uf.same(x, y))   continue;
        uf.unite(x, y);
        graph[x].emplace_back(y, mint(X).pow(z));
        graph[y].emplace_back(x, mint(X).pow(z));
    }
    
    vector<int> dp(N, 1);
    mint ans = 0;
    auto dfs = [&](auto&& self, int from = 0, int par = -1) -> void {
        for(auto [to, cost] : graph[from]){
            if(to == par)   continue;
            self(self, to, from);
            dp[from] += dp[to];
            ans += cost * dp[to] * (N - dp[to]);
        }
    };
    dfs(dfs);
    
    cout << ans << endl;

    return 0;
}