#pragma GCC target("avx2")
#pragma GCC optimize("03")
#pragma GCC optimize("unroll-loops")
#include <bits/stdc++.h>
using namespace std; typedef long double ld; typedef long long ll;
typedef unsigned long long ull;
#define endl "\n"
#define FOR(i,a,b) for(int i=(a);i<=(b);i++)
#define rep(i,n) for(int i=0;i<(n);i++)
#define PII pair<int, int>
#define PLL pair<ll, ll>
#define ALL(x) (x).begin(), (x).end()
constexpr int INF=1<<30; constexpr ll LINF=1LL<<60; constexpr ll mod=1e9+7; constexpr int NIL = -1;
template<class T>vector<T> vec(int len, T elem) { return vector<T>(len, elem); } // auto dp = vec(52, vec(103, vec(103, INF)));
template<class T>inline bool chmax(T &a, const T &b) { if (a<b) { a = b; return 1; } return 0; }
template<class T>inline bool chmin(T &a, const T &b) { if (b<a) { a = b; return 1; } return 0; }
template<class T>inline int popcount(T a) {return __builtin_popcount(a);}
template<class T>inline T emod(T a, T p) { return (a%p + p) % p;}
template <typename T> istream &operator>>(istream &is, vector<T> &vec) { for (auto &v : vec) is >> v; return is; }
template <typename T> ostream &operator<<(ostream &os, const vector<T> &vec) {os << '\n'; for (auto v : vec) os << v << ' '; os << '\n'; return os;}
template <typename T> ostream &operator<<(ostream &os, const deque<T> &vec) { os << "deq["; for (auto v : vec) os << v << ','; os << ']'; return os; }
template <typename T> ostream &operator<<(ostream &os, const set<T> &vec) { os << '{'; for (auto v : vec) os << v << ','; os << '}'; return os; }
template <typename T> ostream &operator<<(ostream &os, const unordered_set<T> &vec) { os << '{'; for (auto v : vec) os << v << ','; os << '}'; return os; }
template <typename T> ostream &operator<<(ostream &os, const multiset<T> &vec) { os << '{'; for (auto v : vec) os << v << ','; os << '}'; return os; }
template <typename T> ostream &operator<<(ostream &os, const unordered_multiset<T> &vec) { os << '{'; for (auto v : vec) os << v << ','; os << '}'; return os; }
template <typename T1, typename T2> ostream &operator<<(ostream &os, const pair<T1, T2> &pa) { os << '(' << pa.first << ',' << pa.second << ')'; return os; }
template <typename TK, typename TV> ostream &operator<<(ostream &os, const map<TK, TV> &mp) { os << '{'; for (auto v : mp) os << v.first << "=>" << v.second << ','; os << '}'; return os; }
template <typename TK, typename TV> ostream &operator<<(ostream &os, const unordered_map<TK, TV> &mp) { os << '{'; for (auto v : mp) os << v.first << "=>" << v.second << ','; os << '}'; return os; }
//-------------------

struct mint {
	ll x;
	mint(ll x=0):x(x%mod){}

	bool operator==(const mint a)const{return x==a.x;}
	bool operator!=(const mint a)const{return x!=a.x;}
	bool operator>=(const mint a){return (x >= a.x)? 1: 0;}
	bool operator<(const mint a){return !(*this>=a);}
	bool operator>(const mint a){return (x > a.x)? 1:0;}
	bool operator<=(const mint a){return !(*this>a);}
	mint& operator+=(const mint a) {
		if ((x += a.x) >= mod) x -= mod;
			return *this;
	}
	mint& operator-=(const mint a) {
		if ((x += mod-a.x) >= mod) x -= mod;
			return *this;
	}
	mint& operator*=(const mint a) {
		(x *= a.x) %= mod;
		return *this;
	}
	mint& operator/=(const mint a) {
		return (*this) *= a.inv();
	}
	mint operator+(const mint a) const {
		mint res(*this);
		return res+=a;
	}
	mint operator-(const mint a) const {
		mint res(*this);
		return res-=a;
	}
	mint operator*(const mint a) const {
		mint res(*this);
		return res*=a;
	}
	mint operator/(const mint a) const {
		mint res(*this);
		return res/=a;
	}
	mint pow(ll t) const {
		if (!t) return 1;
		mint a = pow(t>>1);
		a *= a;  //2 square
		if (t&1) a *= *this; 
		return a;
	}
	// for prime mod
	mint inv() const {
		return pow(mod-2);
	}
    friend ostream& operator<<(ostream& os, const mint& m){
        os << m.x;
        return os;
    }
};
class UnionFind {
private:
	unsigned size_; std::vector<int> par, rank; //par = root? -size: par 
public:
	UnionFind() : size_(0), par(std::vector<int>()), rank(std::vector<int>()) {};
	UnionFind(unsigned size__) : size_(size__) {
		par.resize(size_+1); rank.resize(size_+1);
		for (unsigned i = 0; i <= size_; i++) par[i] = -1, rank[i] = 0;
	}
	//unsigned size() { return size_; }
	unsigned root(unsigned x) {return par[x] < 0 ? x : par[x] = root(par[x]); }
	bool same(unsigned x, unsigned y) { return root(x) == root(y); }
	void unite(unsigned x, unsigned y) {
		x = root(x), y = root(y);
		if (x == y) return;
		if (rank[x] < rank[y])par[y] += par[x], par[x] = y;
		else if (rank[x] == rank[y])par[x] += par[y], par[y] = x, rank[x]++;
		else par[x] += par[y], par[y] = x;
	}
	int size(int x){ return -par[root(x)];} 
	bool operator==(const UnionFind &u) { return par == u.par; }
	bool operator!=(const UnionFind &u) { return par != u.par; }
};

constexpr int MX = 2e5+5;
vector<PLL> G[MX];
mint ans = 0;
ll n,m,x;
ll dfs(int c, int par) {
    ll res=0;
    for(auto [to, cost]: G[c]) {
        if(to==par) continue;
        ll cur = dfs(to, c);
        ans += mint(x).pow(cost) * (n - cur) * cur;
        // cout << cur << endl;
        res += cur; 
    }
    return res+1;
}


int main() {
    cin.tie(0); ios::sync_with_stdio(false); cout << fixed << setprecision(15);
    cin >> n >> m >> x;
    UnionFind uf(n);
    rep(i, m) {
        int x1,y1; cin >> x1 >> y1;
        x1--; y1--;
        ll z; cin >> z;
        if(!uf.same(x1,y1)) {
            uf.unite(x1,y1);
            G[x1].emplace_back(y1, z);
            G[y1].emplace_back(x1, z);
        }
    }
    // rep(i, n) {
    //     cout << G[i] << endl;
    // }
    dfs(0, -1);
    cout << ans << endl;
    return 0;
}