#include<bits/stdc++.h>
using namespace std;
int n, m;
int a[1111][1111];
int main(){
cin>>n>>m;
for(int i = 1;i <= n;i++){
for(int j = 1;j <= n;j++) a[i][j] = 1e9;
}//初始化邻接矩阵为1e9方便判断重边
for(int i = 1;i <= m;i++){
int x, y, z;
cin>>x>>y>>z;
a[x][y] = min(a[x][y], z);//存入邻阶矩阵
if(x == y) a[x][y] = 0;//去除自环
}
