#include <iostream>
using namespace std;
int main(){
long long a, answer=0, power_of_2=1;
int n, bits[64]={0}, i=0;
cin>>a>>n;
while(a!=0){
if(a%2==0){
bits[i]=0;
a/=2;
}
else {
bits[i]=1;
a=(a-1)/2;
}
i++;
}
bits[n-1]=1-bits[n-1];
for(int j=0; j<i; j++) {
if (bits[j] == 1)
answer += power_of_2;
power_of_2 *= 2;
}
cout<<answer;
}