#include<bits/stdc++.h>
using namespace std;
const int MX=2e5+6;
int n,m, dp[MX],a,b;
vector<vector<pair<int,int>>>adj;
int solve(int x)
{
    int ans=1e9;
    if(dp[x]!=-1)return dp[x];
    if(x==b)return 0;
    for(auto u : adj[x])
    {
        ans=min(ans,u.second+solve(u.first));
    }
    return dp[x]=ans;
}
int main()
{
    memset(dp,-1,sizeof dp);
    scanf("%d%d",&n,&m);
    adj.resize(n+3);
    for(int i=0;i<m;i++)
    {
        int x,y,z;
        scanf("%d%d%d",&x,&y,&z);
        adj[x].push_back({y,z});
    }
    scanf("%d%d",&a,&b);
    cout<<solve(a);
return 0;
}