#include<bits/stdc++.h>
#define MAX 1001
#define INF 1e9
#define fastio ios_base::sync_with_stdio(false); cin.tie(NULL);
using namespace std;
int v, e, k, dist[MAX] = {}, goal;
vector<pair<int, int>> arr[MAX];
int main() {
    fastio;
    cin >> e >> v;
    for (int a, b, c, i = 0; i < v; i++) {
        cin >> a >> b >> c;
        arr[a].push_back({ b,c });
    }
    for (int i = 0; i <= e; i++) dist[i] = INF;
    priority_queue<pair<int, int>> q;
    cin >> k >> goal;
    q.push({ 0,k });
    dist[k] = 0;
    while (!q.empty()) {
        int cost = -q.top().first, idx = q.top().second;
        q.pop();
        if (dist[idx] < cost) continue;
        for (int i = 0; i < arr[idx].size(); i++) {
            int next = arr[idx][i].first, next_cost = arr[idx][i].second;
            if (dist[next] > dist[idx] + next_cost) {
                dist[next] = dist[idx] + next_cost;
                q.push({ -dist[next],next });
            }
        }
    }
    cout << dist[goal];
}