繁华模拟赛 Evensgn的债务

#include<iostream>
#include<cstdio>
#include<string>
#include<cstring>
#include<algorithm>
#define ll int
using namespace std;
const int maxn = ;
ll read(){
    ll x=,f=;char ch=getchar();
    while(ch<''||ch>''){if(ch=='-')f=-;ch=getchar();}
    while(ch>=''&&ch<=''){x=x*+ch-'';ch=getchar();}
    return x*f;
}
int v[maxn],sum;
int n,m,a,b,c;
int main(){
    freopen("debt.in","r",stdin);
    freopen("debt.out","w",stdout);
    n = read();
    m = read();
    for(int i = ;i <= m;i++){
        a = read();
        b = read();
        c = read();
        v[a] -= c;
        v[b] += c;
    }
    for(int i = ;i <= n;i++){
        if(v[i] >= ) sum += v[i];
        else sum -= v[i];
    }
    sum >>= ;
    cout<<sum;
    return ;
}