#include<iostream> 
#include<cstring> 
#include<cstdio> 
#include<string> 
#include<algorithm> 
#include<cmath> 
#include<utility> 
#include<stdio.h> 
#include<cstdlib> 
#include<iomanip> //cout<<setiosflags(ios::fixed)<<setprecision(2); 
#include<ctime> //double a=(double)clock();   cout<<a<<endl; 
#include<vector> 
#include<queue> 
using namespace std;
int N,M;
int main()
{
	freopen("tria.in","r",stdin);
	freopen("tria.out","w",stdout);
	scanf("%d %d",&N,&M);
	if(M)
		printf("0\n");
	else if(N<=2)
		printf("1\n");
	else if(N%2)
		printf("%d\n",N+1);
	else 
		printf("%d\n",2*N);
	fclose(stdin),fclose(stdout);
	return 0;
}