#include <fstream>
#include <iostream>
using namespace std;

#define MAX_CIUR 120000

long long unsigned nr, s=0, a, factori[30];

int prime[78500];
bool isprim [1000001];

ifstream in ("frac.in");
ofstream out ("frac.out");

void gen ()
{
    int t=0;
    int i, j;
    for (i = 2; i <= MAX_CIUR; ++i)
        isprim[i] = 1;
    for (i = 2; i <= MAX_CIUR; ++i)
        if (isprim[i])
        {
            for (j = i+i; j <= MAX_CIUR; j += i)
                isprim[j] = 0;
            prime[t]=i;
            t++;
        }
}

void factprimi (long long unsigned int b)
{
    int i = 0;
    nr = 0;
    while(i <= 78500 && prime[i] != 0)  //dc am ajuns la capat si prime[i]=0 nu trebe sa impartim la 0
    {
            if(b%prime[i]==0)
            {
                factori[nr]=prime[i];
                ++nr;
                while(b%prime[i]==0)
                    b=b/prime[i];  //scapam de divizorii primi in plus
            }
            else ++i;
    }
    if(b>MAX_CIUR)
        {
            factori[nr]=b;
            b=1;
            nr++;
        }
}

long long unsigned int pinex()
{
    long long unsigned int sol=0, p, cnt;
        for (int i=1; i < (1<<nr); ++i)
        {
            p=1;
            cnt=0;
            for(int j = 0; j < nr; ++j)
                if((1<<j) & i)
                    {
                        p=1LL*p*factori[j];
                        ++cnt;
                    }
            if(cnt%2==1)
                sol=sol+a/p;
            else
                sol=sol-a/p;
        }
    return sol;
}

int main()
{
    uint64_t b, cautat, st = 1, dr=1 , mid;
    gen ();
    dr=dr<<61;
    in>>a>>cautat;
    while (st < dr)
    {
        //cout<<"CAUT IN "<<st<<" "<<dr<<"\n";
        mid = (st + dr)/2;
        factprimi(a);
        if (mid - pinex() == cautat)
            break;
        else if (mid - pinex() <cautat)
            st=mid+1;
        else
            dr=mid;
    }

    out<<prime[mid - pinex()];

    in.close();
    out.close();
    return 0;
}