#include<iostream>
#include<fstream>
using namespace std;
int a, b;

int main()
{
	ifstream fin("adunare.in");
	fin>>a>>b;
	ofstream fout("adunare.out");
	if((a+b)%2==0)
	fout<<0;
	else
		fout<<a+b;
	fin.close();
	fout.close();
	return 0;
}