#include<iostream>
using namespace std;
int main()
{
void printresult(int firstnumber,int secondnumber){
    if(firstnumber<0||secondnumber<0){
        cout<<"Invalid input"<<endl;
    }
    else if (firstnumber%2==0 && secondnumber%2==0){
        cout<<firstnumber*secondnumber<<endl;
    }
    else if(firstnumber%2!=0 && secondnumber%2!=0){
        cout<<firstnumber+secondnumber<<endl;
    }
    else{
        cout<<firstnumber-secondnumber<<endl;
    }
}
int main()
{
    int firstnumber,secondnumber;
    cout<<"enter first number:";
    cin>>firstnumber;
    cout<<"enter second number:";
    cin>>secondnumber;
    printresult(firstnumber,secondnumber);
    return 0;
}