#include <stdio.h>
#include <math.h>


char a[4294967300];
long i,j,k,n,q,putere=pow(2,32);

int main()
 {
  FILE *f;
  f=fopen("frac.in","r");
  fscanf(f,"%ld %ld",&n,&k);
  fclose(f);
  
  j=1;i=1;
  while (j<k)
     {i++;
      if (a[i]==0)
          if (n%i==0) {for (q=i*i;q<=putere;q=q+i) 
                          a[q]=1;
                       while (n%i==0) 
                            n=n/2;   
                       }
                 else j++;  
      }
  f=fopen("frac.out","w");
  fprintf(f,"%ld",i);
  fclose(f);
  
  return 0;                      
  }