#include <stdio.h>
#include <stdlib.h>

int main()
{
    FILE *fout, *fin;
    int a,b,c;
    fin=fopen("suc.in", "r");
    fout=fopen("suc.out", "w");
    fscanf(fin, "%d%d", &a, &b);
    c=1;
    b*=2;
    while(b>1){
      b--;
      c*=2;
    }
    if(a<c)
      fprintf(fout, "%d", c-a);
    else
      fprintf(fout, "0");
    fclose(fin);
    fclose(fout);
    return 0;
}