题解

#include<iostream>
#include<algorithm>
using namespace std;
int n, m,s;
int main(){
    cin >>n>>m;
    int mn=(n+m)-max(n,m);
    int x=n,y=m;
    for(int i=1;i<=mn;i++){
        s+=x*y;
        x--;
        y--;
    }
    cout<<s;
    
    return 0;
}