Codeforces Round #420 (Div. 2), problem: (B) Okabe and Banana Trees Solution In C/C++

#include <iostream>
using namespace std;
int main(){
long long int m,b,s=0,x;
cin>>m>>b;
for(int i=0;i<=b;i++){
x=(b-i)*m;
s=max(s,((i+1)*(x+1)*(i+x))/2);
}
cout<<s;

}