#include <iostream>
#include <vector>
using namespace std;

int const infinity = 0x3F3F3F3F;

struct Edge {int v; int w;};

int main () {
    int n, m;
    cin >> n >> m;
    vector <vector <Edge> > adj (n);

    for (int j = 0; j < m; j++) {
        int u, v, w;
        cin >> u >> v >> w;
        u -= 1;
        v -= 1;
        adj[u].push_back ({v, w});
        adj[v].push_back ({u, w});
    }

    vector <int> d (n, infinity);
    d[0] = 0;
    for (int k = 0; k < n - 1; k++) {
        for (int u = 0; u < n; u++)
            for (auto e : adj[u])
                if (d[e.v] > d[u] + e.w)
                    d[e.v] = d[u] + e.w;
    }

    int y = n - 1;
    cout << d[y] << endl;
    return 0;
}