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#include <bits/stdc++.h>
using namespace std;
typedef long long int ll;
#define endl "\n"
 
const double PI = 3.14159265358979;
const ll INF =  1e18 + 7;
const ll MOD = 1e9 + 7;
const ll nax = 2505;
const int LOG = 25;


vector<ll> dijkstra(ll src, vector<pair<ll, ll> > adj[], ll n) {
    vector<ll> distance(n + 1, INF);
    vector<bool> visited(n + 1, false);
    priority_queue<pair<ll, ll>> pq;

    distance[src] = 0;
    pq.push({-distance[src], src});

    while(!pq.empty()) {
        pair<ll, ll> curr = pq.top();
        pq.pop();

        ll currNode = curr.second;
        ll currDist = - curr.first;
        if (visited[currNode]) {
            continue;
        }
        visited[currNode] = true;

        for (auto &v: adj[currNode]) {
            ll neigh = v.first;
            ll wt = v.second;

            if (distance[neigh] > currDist + wt) {
                distance[neigh] = distance[currNode] + wt;
                pq.push({-distance[neigh], neigh});
            }
        }
    }

    return distance;
}


void solve() {
    ll n, m, u, v, d, src;
    cin >> n >> m;

    vector<pair<ll, ll> > adj[n + 1];
    for (int i = 1; i <= m; i++) {
        cin >> u >> v >> d;
        adj[u].push_back({v, d});
        adj[v].push_back({u, d});
    }

    cin >> src;
    vector<ll> distance = dijkstra(src, adj, n);

    ll ans = -1;
    for (int i = 1; i <= n; i++) {
        for (auto &v : adj[i]) {
            ll j = v.first;
            ll l = v.second;
            ans = max(ans, distance[i] + distance[j] + l);
        }
    }

    cout << ans * 5;
}

signed main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    cout.tie(nullptr);

    // int t; cin >> t; while(t--)
    solve();
    return 0;
}