#pragma region template
#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ull = unsigned long long;
using ld = long double;
using vi = vector<int>;
using vvi = vector<vi>;
using vvvi = vector<vvi>;
using vll = vector<ll>;
using vvll = vector<vll>;
using vvvll = vector<vvll>;
using vld = vector<ld>;
using vvld = vector<vld>;
using vvvld = vector<vvld>;
using vs = vector<string>;
using pll = pair<ll, ll>;
using vp = vector<pll>;
template <typename T>
using pqrev = priority_queue<T, vector<T>, greater<T>>;
#define rep(i, n) for (ll i = 0, i##_end = (n); i < i##_end; i++)
#define repb(i, n) for (ll i = (n)-1; i >= 0; i--)
#define repr(i, a, b) for (ll i = (a), i##_end = (b); i < i##_end; i++)
#define reprb(i, a, b) for (ll i = (b)-1, i##_end = (a); i >= i##_end; i--)
#define ALL(a) (a).begin(), (a).end()
#define SZ(x) ((ll)(x).size())
//*
constexpr ll MOD = 1e9 + 7;
/*/
constexpr ll MOD = 998244353;
//*/
constexpr ll INF = 1e+18;
constexpr ld EPS = 1e-12L;
constexpr ld PI = 3.14159265358979323846L;
constexpr ll GCD(ll a, ll b) { return b ? GCD(b, a % b) : a; }
constexpr ll LCM(ll a, ll b) { return a / GCD(a, b) * b; }
template <typename S, typename T>
constexpr bool chmax(S &a, const T &b) {
  if (a < b) {
    a = b;
    return 1;
  }
  return 0;
}
template <typename S, typename T>
constexpr bool chmin(S &a, const T &b) {
  if (b < a) {
    a = b;
    return 1;
  }
  return 0;
}
#ifdef OJ_LOCAL
#include "dump.hpp"
#else
#define dump(...) ((void)0)
#endif
template <typename T>
bool print_(const T &a) {
  cout << a;
  return true;
}
template <typename T>
bool print_(const vector<T> &vec) {
  for (auto &a : vec) {
    cout << a;
    if (&a != &vec.back()) {
      cout << " ";
    }
  }
  return false;
}
template <typename T>
bool print_(const vector<vector<T>> &vv) {
  for (auto &v : vv) {
    for (auto &a : v) {
      cout << a;
      if (&a != &v.back()) {
        cout << " ";
      }
    }
    if (&v != &vv.back()) {
      cout << "\n";
    }
  }
  return false;
}
void print() { cout << "\n"; }
template <typename Head, typename... Tail>
void print(Head &&head, Tail &&... tail) {
  bool f = print_(head);
  if (sizeof...(tail) != 0) {
    cout << (f ? " " : "\n");
  }
  print(forward<Tail>(tail)...);
}
#pragma endregion

// ModInt
// 参考：https://ei1333.github.io/luzhiled/snippets/math/mod-int.html
// modはコンパイル時に決定
template <ll mod>
struct ModInt {
  ll x;
  ModInt() : x(0) {}
  ModInt(ll y) : x(y >= 0 ? y % mod : (mod - (-y) % mod) % mod) {}
  constexpr ModInt &operator+=(const ModInt &p) {
    if ((x += p.x) >= mod)
      x -= mod;
    return *this;
  }
  constexpr ModInt &operator-=(const ModInt &p) {
    if ((x += mod - p.x) >= mod)
      x -= mod;
    return *this;
  }
  constexpr ModInt &operator*=(const ModInt &p) {
    x = x * p.x % mod;
    return *this;
  }
  constexpr ModInt &operator/=(const ModInt &p) {
    *this *= p.inverse();
    return *this;
  }
  constexpr ModInt operator-() { return ModInt(-x); }
  constexpr ModInt operator+(const ModInt &p) { return ModInt(*this) += p; }
  constexpr ModInt operator-(const ModInt &p) { return ModInt(*this) -= p; }
  constexpr ModInt operator*(const ModInt &p) { return ModInt(*this) *= p; }
  constexpr ModInt operator/(const ModInt &p) { return ModInt(*this) /= p; }
  constexpr bool operator==(const ModInt &p) { return x == p.x; }
  constexpr bool operator!=(const ModInt &p) { return x != p.x; }
  constexpr ModInt inverse() const {
    ll a = x, b = mod, u = 1, v = 0, t;
    while (b > 0) {
      t = a / b;
      swap(a -= t * b, b);
      swap(u -= t * v, v);
    }
    return ModInt(u);
  }
  constexpr ModInt pow(ll n) {
    ModInt ret(1), mul(x);
    while (n > 0) {
      if (n & 1)
        ret *= mul;
      mul *= mul;
      n >>= 1;
    }
    return ret;
  }
  friend ostream &operator<<(ostream &os, const ModInt &p) {
    return os << p.x;
  }
  friend istream &operator>>(istream &is, ModInt &a) {
    ll t;
    is >> t;
    a = ModInt<mod>(t);
    return (is);
  }
};

using mint = ModInt<MOD>;
using vm = vector<mint>;
using vvm = vector<vm>;

constexpr int MAX_FAC = 2000010;
mint fac[MAX_FAC], facinv[MAX_FAC];
void combInit() {
  fac[0] = mint(1);
  for (int i = 0; i < MAX_FAC - 1; i++) {
    fac[i + 1] = fac[i] * (i + 1);
  }
  facinv[MAX_FAC - 1] = fac[MAX_FAC - 1].inverse();
  for (int i = MAX_FAC - 2; i >= 0; i--) {
    facinv[i] = facinv[i + 1] * (i + 1);
  }
}
mint comb(const ll a, const ll b) {
  assert(a < MAX_FAC);
  assert(b < MAX_FAC);
  if (a < 0 || b < 0 || b > a) {
    return mint(0);
  }
  mint ret(1);
  ret *= fac[a];
  ret *= facinv[b];
  ret *= facinv[a - b];
  return ret;
}
mint multicomb(const ll a, const ll b) {
  return comb(a + b - 1, b);
}

template <typename T>
struct Edge {
  int from, to;
  T cost;
  int id;
  Edge(int from_, int to_, T cost_, int id_) : from(from_), to(to_), cost(cost_), id(id_) {}
  Edge(int from_, int to_, T cost_) : from(from_), to(to_), cost(cost_) {}
  Edge(int from_, int to_) : from(from_), to(to_), cost(1) {}
  bool operator<(const Edge<T> &r) {
    return cost < r.cost;
  }
};
template <typename T>
ostream &operator<<(ostream &os, Edge<T> edge) {
  os << edge.from << " -> " << edge.to << " (" << edge.cost << ")";
  return os;
}

// グラフテンプレート(隣接リスト)
template <typename E = Edge<ll>>
struct GraphL {
  // 頂点数、辺数
  int n, m;
  // 隣接リスト
  vector<vector<E>> adj;
  GraphL(int n_)
      : n(n_), m(0), adj(n_) {}

  template <typename... Args>
  void add_edge(int from, int to, Args... args) {
    adj[from].emplace_back(from, to, args...);
    m++;
  }
  vector<E> &operator[](int i) { return adj[i]; }
};
template <typename E = Edge<ll>>
ostream &operator<<(ostream &os, GraphL<E> graph) {
  os << "V = " << graph.n << ", E = " << graph.m << "\n";
  for (const auto &ev : graph.adj) {
    for (const auto &e : ev) {
      os << e << "\n";
    }
  }
  return os;
}

struct UnionFind {
  // 木の頂点数と高さは根の値のみ意味がある
  vector<int> par, sizes, rank;
  int num_groups;
  UnionFind(int n) : par(n), sizes(n, 1), rank(n, 0), num_groups(n) {
    for (int i = 0; i < n; i++)
      par[i] = i;
  }
  int find(int x) {
    if (x == par[x])
      return x;
    return par[x] = find(par[x]); // recursive, editing root
  }
  void unite(int x, int y) {
    x = find(x);
    y = find(y);
    if (x == y)
      return;
    if (rank[x] < rank[y])
      swap(x, y);
    par[y] = x;
    sizes[x] += sizes[y];
    if (rank[x] == rank[y])
      rank[x]++;
    num_groups--;
  }
  bool same(int x, int y) { return find(x) == find(y); }
  int size(int x) { return sizes[find(x)]; }
};



int main() {
  cin.tie(0);
  ios::sync_with_stdio(false);
  cout << fixed << setprecision(20);
  ll n, m, x;
  cin >> n >> m >> x;
  GraphL<Edge<mint>> g(n);
  UnionFind uf(n);
  rep(i, m){
    ll a, b, c;
    cin >> a >> b >> c;
    a--; b--;
    if(!uf.same(a, b)){
      uf.unite(a, b);
      g.add_edge(a, b, mint(x).pow(c));
      g.add_edge(b, a, mint(x).pow(c));
    }
  }
  vector<bool> visited(n, false);
  mint ans = 0;
  vll v(n, 1);
  auto dfs = [&](auto& Self, int node) -> void{
    visited[node] = true;
    for(auto&& e: g[node]){
      if(!visited[e.to]){
        Self(Self, e.to);
        v[node] += v[e.to];
        ans += e.cost*v[e.to]*(n-v[e.to]);
      }
    }
  };
  dfs(dfs, 0);
  dump(g);
  dump(v);
  print(ans);
}