#include <bits/stdc++.h>
using namespace std;
using ll = long long;

int main() {
    int N, M, K; cin >> N >> M >> K;
    vector<vector<pair<int,int>>> G(N);
    for (int i = 0; i < M; i++) {
        int u, v; cin >> u >> v;
        u--, v--;
        int t; cin >> t;
        G[u].push_back({v, t});
        G[v].push_back({u, t});
    }
    queue<pair<int,int>> q;
    vector<vector<bool>> seen(N, vector<bool>(K, false));
    q.push({0, 0});
    seen[0][0] = true;
    while(!q.empty()) {
        auto [u, x] = q.front();
        q.pop();
        for(auto [v, t]: G[u]) {
            int nx = (t+x)%K;
            if(seen[v][nx]) continue;
            seen[v][nx] = true;
            q.push({v, nx});
        }
    }
    for (int x = 0; x < K; x++) {
        if(seen[N-1][x]) {
            cout << x << endl;
            return 0;
        }
    }
}