#include "bits/stdc++.h"
using namespace std;
#define int long long
#define FOR(i, a, b) for(int i=(a);i<(b);i++)
#define RFOR(i, a, b) for(int i=(b-1);i>=(a);i--)
#define REP(i, n) for(int i=0; i<(n); i++)
#define RREP(i, n) for(int i=(n-1); i>=0; i--)
#define REP1(i, n) for(int i=1; i<=(n); i++)
#define RREP1(i, n) for(int i=(n); i>=1; i--)
#define ALL(a) (a).begin(),(a).end()
#define UNIQUE_SORT(l) sort(ALL(l)); l.erase(unique(ALL(l)), l.end());
#define CONTAIN(a, b) find(ALL(a), (b)) != (a).end()
#define out(...) printf(__VA_ARGS__)

int dxy[] = {0, 1, 0, -1, 0};

void solve();
signed main()
{
#if DEBUG
    std::ifstream in("input.txt");
    std::cin.rdbuf(in.rdbuf());
#endif
    cin.tie(0);
    ios::sync_with_stdio(false);
    solve();
    return 0;
}

/*================================*/
#if DEBUG
#define SIZE 100
#else
#define SIZE 123450
#endif

int N,K;

int gcd(int a, int b) {
    if(a < b) swap(a,b);
    int r;
    while ((r=a%b)) {
        a = b;
        b = r;
    }
    return b;
}

vector<int> primes;

void solve() {
    cin>>N>>K;
    FOR(i,2,sqrt(N)+2) {
        bool is_p = true;
        for (int p:primes) {
            if (i%p==0) {
                is_p = false;
                break;
            }
        }
        if (is_p) primes.push_back(i);
    }
    int m = 0;
    int ma = 0;
    FOR(i,2,N) {
        int g = gcd(N,i);
        int k = 0;
        for (int p:primes) {
            if (p>g) break;
            while (g%p==0) {
                k++;
                g /= p;
            }
            if (g==1) break;
        }
        if (g>1) k++;
        if (k<K) continue;
        map<int, int> M;
        int n = i;
        for (int p:primes) {
            if (p*p>n) break;
            while (n%p==0) {
                M[p]++;
                n/=p;
            }
            if (n==1) break;
        }
        if (n>1) M[n]++;
        int cnt = 1;
        for (auto p:M) cnt *= p.second+1;
        if (cnt > ma) {
            ma = cnt;
            m = i;
        }
    }
    
    cout << m << endl;
}