#include<stdio.h>
int n,m,ship[3001][3001],count[3001]={0};
int main(){
int i,j;
scanf("%d %d",&n,&m);
for(i=1;i<=m;i++){
scanf("%d %d %d",&a,&b,&c);
ship[a][b]=c;
}
int min_ship=0;
for(i=1;i<=n;i++){
for(j=1;j<=n;j++){
if(ship[i][j]!=0){
count[i]+=ship[i][j];
}
if(j==n&&count[i]<min_ship){
min_ship=count[i];
}
}
if(i==1){
min_ship=count[1];
}
}
printf("%d",min_ship);
getchar();getchar();
return 0;
}
