#include <bits/stdc++.h>
using namespace std;

vector<int> ress;
int n, m;
int u, v, w;

int main()
{
  while (~scanf("%d %d",&n,&m))
  {
    ress.resize(n, 0);
    while (m--)
    {
      cin >> u >> v >> w;
      if(u==v) continue;
      ress[u - 1] += w;
      ress[v - 1] += w;
    }
    sort(ress.begin(), ress.end());
    cout << ress[0] << endl;
    ress.clear();
  }

  return 0;
}