#include <iostream>
#include <queue>
#include <vector>
#include <cassert>
#include <cstdio>

#ifdef _DEBUG
const int MN = 100;
#else
const int MN = 1000 * 10 + 10;
#endif

using namespace std;

#define ll long long

#define pii pair <ll, int>
#define mp make_pair

const ll inf = (1ll << 55);

priority_queue <pii> h;

vector <ll> g[MN], w[MN];

ll dp[4][MN];
int n;

void dfs(int v, int len, ll ww, int k) {
    if (!len)
        dp[k][v] = min(dp[k][v], ww);
    else {
        for(int i = 0; i < g[v].size(); i ++) {
            int to = g[v][i];
            dfs(to, len - 1, ww + w[v][i], k);
        }
    }
}

void solve(int st, int k) {
    for(int i = 0; i < n; i ++)
        if (dp[k][i] != inf)
            h.push(mp(-dp[k][i], i));
    dp[k][st] = 0;
    while (!h.empty()) {
        int v = h.top().second;
        ll d = -h.top().first;
        h.pop();
        if (d > dp[k][v])
            continue;
        for(int i = 0; i < g[v].size(); i ++) {
            int to = g[v][i];
            ll nw = max(dp[k][v], dp[k - 1][v] +  w[v][i]);
            assert(dp[k][v] < inf);
            if (nw < dp[k][to]) {
                dp[k][to] = nw;
                h.push(mp(-nw, to));
            }
        }
    }
}

int main () {
    freopen("input.txt", "r", stdin);
    freopen("output.txt", "w", stdout);
    fill(&dp[0][0], &dp[0][0] + 4 * MN, inf);
    for(int i = 0; i < MN; i ++)
        dp[0][i] = 0;
    int m, a, b;
    scanf("%d%d", &n, &m);
    for(int i = 0; i < m; i ++) {
        int x, y, z;
        scanf("%d%d%d", &x, &y, &z);
        x --, y --;
        g[x].push_back(y);
        g[y].push_back(x);
        w[x].push_back(z);
        w[y].push_back(z);
    }
    scanf("%d%d", &a, &b);
    a --, b --;
    dfs(a, 1, 0, 1);
    ll best = dp[1][b];
    dfs(a, 2, 0, 2);
    //dfs(a, 3, 0, 3);
    solve(a, 1);
    solve(a, 2);
    //solve(a, 3);
    dp[2][b] = min(dp[2][b], best);
    cout << dp[2][b] << endl;
}