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