#pragma GCC optimize("O3")
#include <bits/stdc++.h> 
using namespace std;
using ll=long long;
using P=pair<ll,ll>;
template<class T> using V=vector<T>; 
#define fi first
#define se second
#define all(v) (v).begin(),(v).end()
const ll inf=(1e18);
//const ll mod=998244353;
const ll mod=1000000007;
ll GCD(ll a,ll b) {return b ? GCD(b,a%b):a;}
ll LCM(ll c,ll d){return c/GCD(c,d)*d;}
struct __INIT{__INIT(){cin.tie(0);ios::sync_with_stdio(false);cout<<fixed<<setprecision(15);}} __init;
template<class T> bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T> bool chmin(T &a, const T &b) { if (a>b) { a=b; return 1; } return 0; }
struct mint{
    using ull=unsigned long long int;
    ull v;
    mint(ll vv=0){s(vv%mod+mod);}
    mint& s(ull vv){
        v=vv<mod?vv:vv-mod;
        return *this;
    }
    //オーバーロード
    mint operator-()const{return mint()-*this;}//符号反転
    mint&operator+=(const mint&val){return s(v+val.v);}
    mint&operator-=(const mint&val){return s(v+mod-val.v);}
    mint&operator*=(const mint&val){
        v=ull(v)*val.v%mod;
        return *this;
    }
    mint&operator/=(const mint&val){return *this*=val.inv();}
    mint operator+(const mint&val){return mint(*this)+=val;}
    mint operator-(const mint&val){return mint(*this)-=val;}
    mint operator*(const mint&val){return mint(*this)*=val;}
    mint operator/(const mint&val){return mint(*this)/=val;}
    mint pow(ull n)const{
        mint res(1),x(*this);
        while(n){
            if(n&1)res*=x;
            x*=x;
            n>>=1;
        }
        return res;
    }
     mint inv()const{return pow(mod-2);}
    //拡張ユークリッドの互除法
    /* mint inv()const{
        int x,y;
        int g=extgcd(v,mod,x,y);
        assert(g==1);
        if(x<0)x+=mod;
        return mint(x);
    }*/
    friend ostream& operator<<(ostream&os,const mint&val){
        return os<<val.v;
    }//出力
    bool operator<(const mint&val)const{return v<val.v;}
    bool operator==(const mint&val)const{return v==val.v;}
    bool operator>(const mint&val)const{return v>val.v;}
};
struct edge{
    ll to,cost;
    edge(ll to,ll cost):to(to),cost(cost) {}
};
vector<vector<edge>> g;
vector<ll> d;
ll n,m;
ll mid;
V<bool> used;
bool dijkstra(ll s){
    for(int i=0;i<n;i++)d[i]=inf;
    used.assign(n,false);
    d[s]=0;
    priority_queue<P,vector<P>,greater<P>> q;
    q.push(P(0,s));//始点を０で置く
    while(!q.empty()){
        ll cur=q.top().se,val=q.top().fi;
        q.pop();
        if(used[cur]||d[cur]<val)continue;
        used[cur]=true;
        for(edge &e:g[cur]){
            if(e.cost>mid)continue;
            if(used[e.to])continue;
            if(d[e.to]>e.cost){
                d[e.to]=e.cost;
                q.push(P(d[e.to],e.to));
            }
        }
    }
    return (*max_element(all(d))<inf);
}
V<ll> get_path(ll t){//頂点tへの最短経路
    V<ll> path;
    for(;t!=-1;t=d[t]){
        path.emplace_back(t);
    }
    reverse(all(path));
    return path;
}
mint ans=0;
V<ll> cnt;
ll D;
void dfs(int cur,int par){
    for(edge &e:g[cur]){
        if(e.to==par)continue;
        if(d[e.to]!=e.cost)continue;
        dfs(e.to,cur);
    }
    for(edge &e:g[cur]){
        if(e.to==par)continue;
        if(d[e.to]!=e.cost)continue;
        ans+=mint(D).pow(e.cost)*mint((cnt[e.to])*(n-cnt[e.to]));
        cnt[cur]+=cnt[e.to];
    }
    cnt[cur]++;
}
int main(){
    cin>>n>>m>>D;
    cnt.assign(n,0);
    d.resize(n);
    g.resize(n);
    ll x,y,z;
    for(int i=0;i<m;i++){
        cin>>x>>y>>z;
        x--;y--;
        g[x].emplace_back(y,z);
        g[y].emplace_back(x,z);
    }
    ll  l=-1,r=(1e9)+7;
    while(r-l>1){
        mid=(l+r)/2;
        if(dijkstra(0))r=mid;
        else l=mid;
    }
    // for(int i=0;i<n;i++)cout<<d[i]<<" ";
    // cout<<"\n";
     dfs(0,-1);
    cout<<ans<<"\n";
}