#line 2 "/Users/kaage/Desktop/ProgrammingWorkspace/library/other/template.hpp"
#define _CRT_SECURE_NO_WARNINGS
#pragma target("avx")
#pragma optimize("O3")
#pragma optimize("unroll-loops")
#include <algorithm>
#include <bitset>
#include <cassert>
#include <cfloat>
#include <climits>
#include <cmath>
#include <complex>
#include <ctime>
#include <deque>
#include <fstream>
#include <functional>
#include <iomanip>
#include <iostream>
#include <iterator>
#include <list>
#include <map>
#include <memory>
#include <queue>
#include <random>
#include <set>
#include <stack>
#include <string>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include <vector>
#define rep(i,n) for(int i=0;i<(lint)(n);i++)
#define REP(i,n) for(int i=1;i<=(lint)(n);i++)
#define all(V) V.begin(),V.end()
typedef long long lint;
typedef unsigned long long ulint;
typedef std::pair<int, int> P;
typedef std::pair<lint, lint> LP;
constexpr int INF = INT_MAX/2;
constexpr lint LINF = LLONG_MAX/2;
constexpr double eps = DBL_EPSILON;
constexpr double PI=3.141592653589793238462643383279;
template<class T>
class prique :public std::priority_queue<T, std::vector<T>, std::greater<T>> {};
template <class T, class U>
inline bool chmax(T& lhs, const U& rhs) {
	if (lhs < rhs) {
		lhs = rhs;
		return 1;
	}
	return 0;
}
template <class T, class U>
inline bool chmin(T& lhs, const U& rhs) {
	if (lhs > rhs) {
		lhs = rhs;
		return 1;
	}
	return 0;
}
inline lint gcd(lint a, lint b) {
	while (b) {
		lint c = a;
		a = b; b = c % b;
	}
	return a;
}
inline lint lcm(lint a, lint b) {
	return a / gcd(a, b) * b;
}
bool isprime(lint n) {
	if (n == 1)return false;
	for (int i = 2; i * i <= n; i++) {
		if (n % i == 0)return false;
	}
	return true;
}
template<typename T>
T mypow(T a, lint b) {
	if (!b)return T(1);
	if (b & 1)return mypow(a, b - 1) * a;
	T memo = mypow(a, b >> 1);
	return memo * memo;
}
lint modpow(lint a, lint b, lint m) {
	if (!b)return 1;
	if (b & 1)return modpow(a, b - 1, m) * a % m;
	lint memo = modpow(a, b >> 1, m);
	return memo * memo % m;
}
template<typename T>
void printArray(std::vector<T>& vec) {
	rep(i, vec.size() - 1)std::cout << vec[i] << " ";
	std::cout << vec.back() << std::endl;
}
template<typename T>
void printArray(T l, T r) {
	T rprev = r;
	rprev--;
	for (T i = l; i != rprev; i++) {
		std::cout << *i << " ";
	}
	std::cout << *rprev << std::endl;
}
#line 3 "/Users/kaage/Desktop/ProgrammingWorkspace/library/graph/UnionFind.hpp"
class UnionFind {
protected:
	std::vector<int> par, rank, size;
public:
	UnionFind(unsigned int size) {
		par.resize(size); rank.resize(size, 0); this->size.resize(size, 1);
		rep(i, size) {
			par[i] = i;
		}
	}
	int find(int n) {
		if (par[n] == n)return n;
		return par[n] = find(par[n]);
	}
	void unite(int n, int m) {
		n = find(n);
		m = find(m);
		if (n == m)return;
		if (rank[n] < rank[m]) {
			par[n] = m;
			size[m] += size[n];
		}
		else {
			par[m] = n;
			size[n] += size[m];
			if (rank[n] == rank[m])rank[n]++;
		}
	}
	bool same(int n, int m) {
		return find(n) == find(m);
	}
	int getsize(int n) {
		return size[find(n)];
	}
};
#line 3 "/Users/kaage/Desktop/ProgrammingWorkspace/library/algebraic/ModInt.hpp"
class ModInt {
    lint value;
public:
    static const unsigned int modulo;
    ModInt() : value(0) {}
    template<typename T>
    ModInt(T value = 0) : value(value) {
        if (value < 0)value = -(lint)(-value % modulo) + modulo;
        this->value = value % modulo;
    }
    inline operator int()const { return value; }
    inline ModInt& operator+=(const ModInt& x) {
        value += x.value;
        if (value >= modulo)value -= modulo;
        return *this;
    }
    inline ModInt& operator++() {
        if (value == modulo - 1)value = 0;
        else value++;
        return *this;
    }
    inline ModInt operator-()const {
        return ModInt(0) -= *this;
    }
    inline ModInt& operator-=(const ModInt& x) {
        value -= x.value;
        if (value < 0)value += modulo;
        return *this;
    }
    inline ModInt& operator--() {
        if (value == 0)value = modulo - 1;
        else value--;
        return *this;
    }
    inline ModInt& operator*=(const ModInt& x) {
        value = value * x.value % modulo;
        return *this;
    }
    inline ModInt& operator/=(ModInt rhs) {
        int exp = modulo - 2;
        while (exp) {
            if (exp & 1)*this *= rhs;
            rhs *= rhs;
            exp >>= 1;
        }
        return *this;
    }
    template<typename T> ModInt operator+(const T& rhs)const { return ModInt(*this) += rhs; }
    template<typename T> ModInt& operator+=(const T& rhs) { return operator+=(ModInt(rhs)); }
    template<typename T> ModInt operator-(const T& rhs)const { return ModInt(*this) -= rhs; }
    template<typename T> ModInt& operator-=(const T& rhs) { return operator-=(ModInt(rhs)); }
    template<typename T> ModInt operator*(const T& rhs)const { return ModInt(*this) *= rhs; }
    template<typename T> ModInt& operator*=(const T& rhs) { return operator*=(ModInt(rhs)); }
    template<typename T> ModInt operator/(const T& rhs)const { return ModInt(*this) /= rhs; }
    template<typename T> ModInt& operator/=(const T& rhs) { return operator/=(ModInt(rhs)); }
};
std::istream& operator>>(std::istream& ist, ModInt& x) {
    lint a;
    ist >> a;
    x = a;
    return ist;
}
#line 4 "main.cpp"
const unsigned int ModInt::modulo=1000000007;
int n,m,x;
ModInt ans;
std::vector<std::pair<int,P>> vec;
std::vector<P> edges[200010];
bool used[200010];
int dfs(int node){
    used[node]=true;
    int cnt=1;
    for(const P& i:edges[node]){
        if(!used[i.first]){
            int s=dfs(i.first);
            ans+=mypow(ModInt(x),i.second)*s*(n-s);
            cnt+=s;
        }
    }
    return cnt;
}
int main(){
	std::cin>>n>>m>>x;
	rep(i,m){
        int a,b,c;
        std::cin>>a>>b>>c;
        vec.push_back({c,{a,b}});
	}
    UnionFind uf(n+1);
    for(const auto& i:vec){
        if(!uf.same(i.second.first,i.second.second)){
            uf.unite(i.second.first,i.second.second);
            edges[i.second.first].emplace_back(i.second.second,i.first);
            edges[i.second.second].emplace_back(i.second.first,i.first);
        }
    }
    dfs(1);
    std::cout<<ans<<std::endl;
}