#include<bits/stdc++.h>
using namespace std;
const int N = 1010;
const int inf = 0x3f3f3f3f;
typedef pair<int, int>PII;
int g[N][N];
int n, m;
int ans;
int dist[N], st[N];
int  dijks(int x,int y) {
    memset(dist, 0x3f, sizeof dist);
    memset(st, 0, sizeof st);
    dist[x] = 0;
    priority_queue<PII, vector<PII>, greater<PII>> heap;
    heap.push({ 0,x });
    while (heap.size())
    {
        PII u = heap.top();
        heap.pop();
        int distant = u.first, ver = u.second;
        if (st[ver]) continue;
        st[ver] = 1;
        for (int i = 1; i <= n; i++) {
            if (dist[i] > dist[ver] + g[ver][i]) {
                dist[i] = dist[ver] + g[ver][i];
                heap.push({ dist[i], i });
            }
        }
    }
    return dist[y];
}

int main() {
    memset(g, 0x3f, sizeof g);
    cin >> n >> m;
    while (m--) {
        int a, b, c;
        cin >> a >> b >> c;
        g[a][b] = c;

    }
    for (int i = 2; i <= n; i++) {
        ans = dijks(1, i) + dijks(i, 1) + ans;
    }
    cout << ans;
}