#include <iostream>
#include <queue>
#include <vector>

using namespace std;
/*
 0: (1, 2)
 1:
 2:
 3:
 4:
 
 
 **/

struct node {
    int index, shortest_cost;
    
    node(int i, int s) {
        index = i;
        shortest_cost = s;
    }
    
    bool operator < (const node &tmp) const {
        return shortest_cost > tmp.shortest_cost;
    }
};

int main()
{
    int n, m; // broj na teminja, broj na rebra
    cin >> n >> m;
    vector<pair<int, int> > graph[n + 5];
    for(int i = 0; i < m; i++) {
        int a, b, c; // temeto A e povrzano so temeto B i odaleceni se so C
        cin >> a >> b >> c;
        graph[a].push_back(make_pair(b, c));
        graph[b].push_back(make_pair(a, c));
    }
    
    int S, E;
    cin >> S >> E;
    // od kade sakam do kade sakam da najdam najkratok pat
    priority_queue<node> pq;
    pq.push(node(S, 0));
    
    vector<bool> visited(n + 1, false);
    
    while(!pq.empty()) {
        node current = pq.top(); // kazi mi koj e najmal sosed
        pq.pop();
        
        visited[current.index] = true;
        if(current.index == E) {
            cout << current.shortest_cost << endl; // ova e najkratkiot pat
            break;
        }
        
        for(int i = 0; i < graph[current.index].size(); i++) {
            int sosed = graph[current.index][i].first;
            int pat = graph[current.index][i].second;
            
            if(!visited[sosed]) {
                pq.push(node(sosed, current.shortest_cost + pat));
            }
            
        }
    }
    return 0;
}