#include <iostream>
#include <vector>
#include <queue>
#include <climits>
#include <fstream>
using namespace std;

ifstream fin("dijkstra.in");
ofstream gout("dijkstra.out");
int main(){
    unsigned long long int n,m;
    fin>>n>>m;
    vector<vector<pair<int, int>>> adj(n+1);
    for(int i=0;i<m;i++){
        int u,v,p;
        fin>>u>>v>>p;
        adj[u].push_back({v, p});
    }
    
   
    priority_queue<pair<int,int>, vector<pair<int,int>>, greater<pair<int,int>>> pq;
    vector<unsigned long long int> dist(n+1, ULLONG_MAX);
    pq.push({0, 1});
    dist[st] = 0;
    while(!pq.empty()){
        auto [d, node] = pq.top();
        pq.pop();
        if(d > dist[node]) continue;
        for(auto [nei, weight]: adj[node]){
            if(dist[node] + weight < dist[nei]){
                dist[nei] = dist[node] + weight;
                pq.push({dist[nei], nei});
            }
        }
    }
    if(dist[fn] == ULLONG_MAX){
        gout<<-1<<endl;
    } else {
        gout<<dist[fn]<<endl;
    }

    return 0;
}