#include <fstream>
using namespace std;

ifstream f("gfact.in");
ofstream g("gfact.out");

const long long N=200000000;
long long a[N+1];
int putere (int x, int p){
    int s=0;
    while(x!=0){
        s=s+x/p;
        x=x/p;
    }
    return s;
}
int main()
{
    int q,p,pas=1<<30;
    long long i,j;
    f>>p>>q;
    for(i=2;i<=p;i++)
        if(a[i]==0)
        for(j=i;j<=p;j+=i)
            a[j]=i;
    //g<<a[21];
    i=0;
    while(pas!=0){
        if(putere(i+pas,a[p])<q)
            i+=pas;
        pas/=2;
    }
    g<<i+1;
    return 0;
}