gg，y一下就是每一个点到根的距离用rank维护，，
#include <cstdio>
#include <iostream>
#include <algorithm>
#include <string.h>
#include <vector>
#include <queue>
#include <math.h>
#include <set>
using namespace std;
#define mod 1000000007
#define ll int
#define rank Rank
#define N 100100
ll n;
ll f[N], rank[N];
ll find(ll x){
if(x==f[x]) return x;
int t = f[x];
f[x] = find(f[x]);
rank[x] += rank[t];
return f[x];
}
bool Union(int x, int y, int m){
int fx = find(x), fy = find(y);
if(fx==fy)
{
if(rank[x] + m != rank[y])
return false;
return true;
}
f[fy] = fx;
rank[fy] = rank[x] + m -rank[y];
return true;
}
void init(){
for(int i = 0; i <= n; i++)
f[i] = i, rank[i] = 0;
}
int main(){
int i, j, u, v, d, que;
while(~scanf("%d %d",&n,&que)) {
init();
int ans = 0;
while(que--)
{
scanf("%d %d %d",&u,&v,&d);
if(Union(u,v,d)==false)
ans++;
}
cout<<ans<<endl;
}
return 0;
}
/*
*/