#include <cstdio>

namespace pre{

  inline void read(int &sum){

    register char ch=getchar();

    for(sum=;ch<''||ch>'';ch=getchar());

    for(;ch>=''&&ch<='';sum=(sum<<)+(sum<<)+ch-'',ch=getchar());

  }

}

namespace P=pre;

namespace wq{

  int n,m;

  int a[];

  inline void Work(){

    using P :: read;

    read(n),read(m);

    for(int i=,A,B,C;i<=m;i++){

      read(A),read(B),read(C);

      a[A]-=C,a[B]+=C;

    }

  }

}

int main(){

  wq::Work();

  int ans=;

  for(int i=;i<=wq::n;i++){

    if(wq::a[i]>)

      ans+=wq::a[i];

  }

  printf("%d",ans);

  return ;

}