以下代码

#include<iostream>
using namespace std;
int main()
{
    unsigned long long a,b;
    unsigned long long p,q;
    cin>>a>>b>>p>>q;
    if(p==0||q==0)
        if(a % max(p,q) == 0 && b % max(p,q) == 0) cout<<"YES";else cout<<"NO";
    else 
        if(min(a,b)*max(p,q)<max(a,b)*min(p,q)) 
            cout<<"NO";
        else
        if((a % (p+q) + b % (p+q))%(p+q)==0) 
            cout<<"YES"; 
        else 
            cout<<"NO";
}

其中，为什么

if(a % max(p,q) == 0 && b % max(p,q) == 0) cout<<"YES";else cout<<"NO";

会报错？