求大佬讲解RE的原因

#include <cstdio>
#include <algorithm>
using namespace std;
int n,m,answer;
int zheng(int ans,int sum){
	if(sum>min(n,m)) return ans;
	ans+=((n-sum+1)*(m-sum+1));
	zheng(ans,sum+1);
}
int main(){
	scanf("%d%d",&n,&m);
	printf("%d ",zheng(0,1));
	for(int i=1;i<=n;i++){
		for(int j=1;j<=m;j++){
			if(i==j) continue;
			answer+=(n-i+1)*(m-j+1);
		}
	}
	printf("%d",answer);
	return 0;
}