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