what？输出0，为什么？！求大佬帮看

#include<bits/stdc++.h>
using namespace std;
struct tot{
	int a,b;
}lca[51];
struct sb{
	int k;
}lcb[51];
int n,m,cnt;
int c[51],h[51],jdb[21][21],x[51],y[51];
//bool cmp(int x,int y){
//	return x.k>y.k;
//}
int main(){
	cin>>n>>m;
	for(int i=1;i<=m;i++){
		cin>>lca[i].a>>lca[i].b>>lcb[i].k;
		if(lcb[i].k<lcb[i+1].k){
			swap(lcb[i].k,lcb[i+1].k);
			swap(lca[i].a,lca[i+1].a);
			swap(lca[i].b,lca[i+1].b);
		}
		c[lca[i].a++];
		h[lca[i].b++];
	}
	//sort(lcb+1,lcb+m+1,cmp);
	for(int i=1;i<=m;i++){
		if(c[lca[i].a]>=1&&h[lca[i].b]>=1&&x[i]==0&&y[i]==0){
			cnt=cnt+lcb[i].k;
			x[i]=1;
			y[i]=1;
		}
	}
	cout<<cnt;
	return 0;
}