unknow error咋回事？

#include<bits/stdc++.h>
using namespace std;
int main(){
	int a,n,m;
	cin>>a>>n>>m;
	int l,r;
	if(n%a==0){
		l=n/a;
	}else l=n/a+1;
	if(m%a==0){
		r=m/a;
	}else r=m/a+1;
	cout<<l*r;
	return 0;
}

用户名：jiabokai__