#include <algorithm>
#include <cmath>
#include <iomanip>
#include <iostream>
#include <map>
#include <numeric>
#include <queue>
#include <tuple>
#include <vector>
using namespace std;
using ll = int64_t;
#define rep(i, j, n) for (int i = j; i < (int)n; ++i)
#define rrep(i, j, n) for (int i = (int)n - 1; j <= i; --i)

constexpr ll MOD = 1000000007;
constexpr int INF = 0x3f3f3f3f;
constexpr ll INFL = 0x3f3f3f3f3f3f3f3fLL;

struct UnionFind {
  vector<int> par;
  UnionFind(int n) : par(n, -1) {}
  void unite(int x, int y) {
    x = find(x);
    y = find(y);
    if (x == y) return;
    if (par[x] > par[y]) swap(x, y);
    par[x] += par[y];
    par[y] = x;
    return;
  }
  bool same(int x, int y) { return find(x) == find(y); }
  int find(int x) {
    if (par[x] < 0) return x;
    int r = find(par[x]);
    return par[x] = r;
  }
  int sizeOf(int x) { return -par[find(x)]; }
};

struct Edge {
  int from, to;
  int64_t cost;
  Edge(int f, int t, int64_t c) : from(f), to(t), cost(c) {}
  bool operator<(const Edge& e) const { return cost < e.cost; }
};
using Edges = vector<Edge>;

Edges kruskal(Edges& es, int n) {
  UnionFind uf(n);
  sort(es.begin(), es.end());
  Edges mst;

  for (Edge e : es) {
    if (!uf.same(e.from, e.to)) {
      uf.unite(e.from, e.to);
      mst.push_back(e);
    }
  }
  return mst;
}

ll mpow(ll x, ll e) {
  ll res = 1;
  while (e) {
    if (e & 1) res = res * x % MOD;
    x = x * x % MOD;
    e >>= 1;
  }
  return res;
}

ll dfs1(int v, int p, vector<ll>& d, vector<vector<pair<int, ll>>>& g) {
  ll res = 1;
  for (auto e : g[v]) {
    int nv = e.first;
    if (nv == p) continue;
    res += dfs1(nv, v, d, g);
  }
  d[v] = res;
  return res;
}

ll ans = 0;
ll n, m, x;
void dfs2(int v, int p, vector<ll>& d, vector<vector<pair<int, ll>>>& g) {
  for (auto e : g[v]) {
    int nv = e.first;
    if (nv == p) continue;
    ans = (ans + d[nv] * (n - d[nv]) * mpow(x, e.second) % MOD) % MOD;
    dfs2(nv, v, d, g);
  }
}

int main() {
  ll a, b, c;
  cin >> n >> m >> x;
  Edges es;
  rep(i, 0, m) {
    cin >> a >> b >> c;
    --a, --b;
    es.emplace_back(a, b, c);
  }
  auto mst = kruskal(es, n);
  vector<vector<pair<int, ll>>> g(n);
  rep(i, 0, mst.size()) {
    int from = mst[i].from;
    int to = mst[i].to;
    ll cost = mst[i].cost;
    g[from].emplace_back(to, cost);
    g[to].emplace_back(from, cost);
  }
  vector<ll> d(n);
  dfs1(0, 0, d, g);
  dfs2(0, 0, d, g);
  cout << ans << endl;
}