/* -*- coding: utf-8 -*-
 *
 * 1207.cc:  No.1207 グラフX - yukicoder
 */

#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<iostream>
#include<string>
#include<vector>
#include<map>
#include<set>
#include<stack>
#include<list>
#include<queue>
#include<deque>
#include<algorithm>
#include<numeric>
#include<utility>
#include<complex>
#include<functional>
 
using namespace std;

/* constant */

const int MAX_N = 200000;
const int MOD = 1000000007;

/* typedef */

typedef long long ll;
typedef queue<int> qi;
typedef pair<int,int> pii;
typedef vector<pii> vpii;

struct UFT {
  int links[MAX_N], ranks[MAX_N], sizes[MAX_N];
  UFT() {}

  void init(int n) {
    for (int i = 0; i < n; i++) links[i] = i, ranks[i] = sizes[i] = 1;
  }

  int root(int i) {
    int i0 = i;
    while (links[i0] != i0) i0 = links[i0];
    return (links[i] = i0);
  }

  int rank(int i) { return ranks[root(i)]; }
  int size(int i) { return sizes[root(i)]; }
  bool same(int i, int j) { return root(i) == root(j); }

  int merge(int i0, int i1) {
    int r0 = root(i0), r1 = root(i1), mr;
    if (r0 == r1) return r0;
    if (ranks[r0] == ranks[r1]) {
      links[r1] = r0;
      sizes[r0] += sizes[r1];
      ranks[r0]++;
      mr = r0;
    }
    else if (ranks[r0] > ranks[r1]) {
      links[r1] = r0;
      sizes[r0] += sizes[r1];
      mr = r0;
    }
    else {
      links[r0] = r1;
      sizes[r1] += sizes[r0];
      mr = r1;
    }
    return mr;
  }
};

/* global variables */

UFT uft;
vpii nbrs[MAX_N];
int ps[MAX_N], pws[MAX_N], cns[MAX_N], ss[MAX_N];

/* subroutines */

int powmod(int a, int n) {  // a^n % MOD
  int pm = 1;
  while (n > 0) {
    if (n & 1) pm = (ll)pm * a % MOD;
    a = (ll)a * a % MOD;
    n >>= 1;
  }
  return pm;
}

/* main */

int main() {
  int n, m, x;
  scanf("%d%d%d", &n, &m, &x);

  uft.init(n);

  for (int i = 0; i < m; i++) {
    int xi, yi, zi;
    scanf("%d%d%d", &xi, &yi, &zi);
    xi--, yi--;

    if (! uft.same(xi, yi)) {
      uft.merge(xi, yi);
      int wi = powmod(x, zi);
      nbrs[xi].push_back(pii(yi, wi));
      nbrs[yi].push_back(pii(xi, wi));
    }
  }

  ps[0] = -1;
  qi q;
  q.push(0);

  while (! q.empty()) {
    int u = q.front(); q.pop();
    int up = ps[u];
    vpii &nbru = nbrs[u];
    for (vpii::iterator vit = nbru.begin(); vit != nbru.end(); vit++) {
      int v = vit->first;
      if (v != up) {
	ps[v] = u;
	pws[v] = vit->second;
	cns[u]++;
	q.push(v);
      }
    }
  }

  for (int u = 0; u < n; u++)
    if (cns[u] == 0) q.push(u);

  int sum = 0;
  while (! q.empty()) {
    int u = q.front(); q.pop();
    ss[u]++;

    int up = ps[u];
    if (up >= 0) {
      sum = (sum + (ll)pws[u] * ss[u] % MOD * (n - ss[u]) % MOD) % MOD;
      ss[up] += ss[u];
      if (--cns[up] == 0) q.push(up);
    }
  }

  printf("%d\n", sum);
  return 0;
}