#include <iostream>
#include<cmath>
 using namespace std;
 void solve() {
     int A, B;
     if(!(cin >> A >> B)){
         return;
     }
     if(A < 0 || B < 0){
         cout << "Invalid input" << endl;
         return;
     }
     
     bool isA_Even = (A % 2 == 0);
     bool isB_Even = (B % 2 == 0);
 
     int result;
     if(isA_Even && isB_Even){
         result = A + B;
         
     else if (!isA_Even && isB_Even){
         result = A + B;
 }
 else{
     result = abs(A - B);
 }
 int main(){
     ios_base::sync_with_stdio(false);
     cin.tie(NULL);
     
     solve();
     return 0;
 }