#include <bits/stdc++.h>
using namespace std;

int cnt[100010];
bool jg[100010];
vector<int> p;

void judge_search(long long cur, long long curi, long long c, vector<pair<long long, int>> &v, long long k) {
    jg[cur] = (c >= k);
    if (curi == v.size()) return;
    for (int i = 0; i <= v[curi].second; i++) {
        judge_search(cur, curi+1, c+i, v, k);
        cur *= v[curi].first;
    }
}

void judge(long long n, long long k) {
    map<long long, int> m;
    for (long long i = 2; i * i <= n; i++) {
        while (n % i == 0) {
            m[i]++; n /= i;
        }
    }
    if (n != 1) m[n]++;
    vector<pair<long long, int>> v;
    for (auto it: m) {
        v.emplace_back(it);
    }
    judge_search(1, 0, 0, v, k);
}

void search(long long cur, long long curi, long long num) {
    cnt[cur] = num;
    if (curi == p.size()) return;
    if (p[curi] * cur > 100000) return;
    long long next = cur; long long u = 0;
    while (next <= 100000) {
        search(next, curi+1, num*(u+1));
        next *= p[curi]; u++;
    }
}

vector<bool> Eratosthenes(int n){
	vector<bool> prime(n+1, true);
	if(n >= 0) prime[0] = false;
	if(n >= 1) prime[1] = false;
	for(int i = 2; i * i <= n; i++){
		if(prime[i]){
			for(int j = i + i; j <= n; j += i) prime[j] = false;
		}
	}
	return prime;
}

long long gcd(long long a, long long b) {
    if (a % b == 0) return b;
    else return gcd(b, a % b);
}

int main() {
    auto b = Eratosthenes(100000);
    for (int i = 0; i <= b.size(); i++) if (b[i]) p.emplace_back(i);
    search(1, 0, 1);
    long long n, k; cin >> n >> k;
    judge(n, k);
    long long best = 0; long long ans = 0;
    for (long long i = 1; i < n; i++) {
        if (jg[gcd(i, n)] && best < cnt[i]) {
            best = cnt[i]; ans = i;
        }
    }
    cout << ans << endl;
    return 0;
}