#include <bits/stdc++.h>

using namespace std;

#define REP(i,n) for(int i=0; i<(int)(n); i++)
#define FOR(i,b,e) for (int i=(int)(b); i<(int)(e); i++)
#define ALL(x) (x).begin(), (x).end()

const double PI = acos(-1);

class UFT {
  int n;
  int cnt;           // number of connected components
  vector<int> par;
  vector<int> rank;
  vector<int> sz;    // size of each component
public:
  UFT(int n) : n(n), cnt(n), par(n), rank(n), sz(n) {
    for (int i = 0; i < n; i++) {
      par[i] = i;
      sz[i] = 1;
    }
  }
  
  int find(int x) {
    return par[x] == x ? x : par[x] = find(par[x]);
  }
  
  void unite(int x, int y) {
    x = find(x);
    y = find(y);
    if (x == y) return;
    
    --cnt;
    if (rank[x] < rank[y]) {
      par[x] = y;
      sz[y] += sz[x];
    } else {
      par[y] = x;
      sz[x] += sz[y];
      if (rank[x] == rank[y])
        ++rank[x];
    }
    
  }
  
  bool same(int x, int y) {
    return find(x) == find(y);
  }
  
  int compCnt() {
    return cnt;
  }
  
  int size(int x) {
    return sz[find(x)];
  }
};

long long modpow(long long x, long long p, long long mod) {
  long long ret = 1;
  while (p) {
    if (p & 1)
      ret = ret * x % mod;
    x = x * x % mod;
    p >>= 1;
  }
  return ret;
}

const long long MOD = 1e9 + 7;
int n, m;
vector<pair<int, long long> > edges[200000];
long long ret = 0;


int dfs(int v, int par = -1) {
  int c = 1;
  for (auto &[u, dist]: edges[v]) {
    if (u == par) continue;
    int ch = dfs(u, v);
    c += ch;
    ret += dist * ch % MOD * (n - ch) % MOD;
    ret %= MOD;
  }
  return c;
}

int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);

  long long x;
  cin >> n >> m >> x;

  UFT tree(n);
  REP (i, m) {
    int u, v, z;
    cin >> u >> v >> z;
    --u, --v;
    if (tree.same(u, v))
      continue;
    else {
      tree.unite(u, v);
      long long dist = modpow(x, z, MOD);
      edges[u].emplace_back(v, dist);
      edges[v].emplace_back(u, dist);
    }
  }

  dfs(0);
  
  cout << ret << endl;
  
  return 0;
}