// editor1
#include<iostream>
using namespace std;
int main(){
    if(-100<=a<=100 && -100<=b<=100){
        if(a<0||b<0){
            cout<<"Invalid input";
            
        }
        else if(a%2==0 && b%2==0){
            cout<<a*b<,endl;
        }
        else{
            cout<<abs(a-b);
            
        }
    }
    return 0;
}