#include <stdio.h>
#include <math.h>
long long nr[100],i,j,d,n,p;
int main(){
	FILE*f=fopen("frac.in","r");
	FILE*g=fopen("frac.out","w");
	fscanf(f,"%lld",&n);
	fscanf(f,"%lld",&p);
	for(i=2;i<=sqrt(n);i++)
		if(n%i==0&&!nr[i])
			for(j=1;j<=100;j++)
				nr[i*j]=1;
	for(i=1;i<=100;i++){
		if(nr[i]==0)p--;
		if(!p)break;
	}
	fprintf(g,"%lld",i);
	return 0;
}