#include <bits/stdc++.h>
using namespace std;
#define modulo 1000000007
#define mod(mod_x) ((((long long)mod_x+modulo))%modulo)
#define Inf 10000000000000

int main(){
	
	int N,K;
	cin>>N>>K;
	int T = K+1;
	if(N%2==0){
		cout<<min(T,N/2)<<endl;
	}
	else{
		cout<<min(T,N)<<endl;
	}
	
	
	return 0;
}