#include <bits/stdc++.h>
#define mp make_pair
#define ll long long
using namespace std;
ifstream fin("gfact.in");
ofstream fout("gfact.out");
int p,q,a;
ll b;
pair <int, int>f;
pair<int,int> desc(int p)
{
    int mxp,mxs=0,ex,d;
    while(p%2==0)p/=2,mxs++,mxp=2;
    d=3;
    while(p!=1)
    {
        ex=0;
        while(p%d==0)p/=d,mxp=d,ex++;
        if(mxp==d)mxs=ex;
        d+=2;
        if(d>sqrt(p))d=p;
    }
    return mp(mxp,mxs);
}
ll nr(ll n)
{
    ll s=0;
    while(n)
    {
        s+=n/a;
        n/=a;
    }
    return s;
}
ll caut(int a)
{
    ll s=1,d=LLONG_MAX,m,best;
    while(s<=d)
    {
        m=s+(d-s)/2;
        if(nr(m)>=b)
        {
            best=m;
            d=m-1;
        }
        else s=m+1;
    }
    if(nr(best)<b)return -1;
    return best;
}
int main()
{
    fin>>p>>q;
    f=desc(p);
    a=f.first;
    b=(ll)f.second*q;
    fout<<caut(a)<<"\n";
    return 0;
}