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

int main() {
    int N, K;
    cin >> N >> K;
    vector<vector<int>> fact(N + 1);
    vector<int> num(N + 1, 1);
    for (int i = 1; i < N; i++) {
        for (int j = 1; j * j <= i; j++) {
            if (i % j) continue;
            fact[i].push_back(j);
            if (j * j != i) fact[i].push_back(i / j);
        }
    }
    num[1] = 0;
    for (int i = 2; i * i < N; i++) {
        if (num[i] != 1) continue;
        for (int j = 2; i * j < N; j++) num[i * j] = num[i] + num[j];
    }
    int max = 0, res = 0;
    for (int i = 1; i < N; i++) {
        if (num[__gcd(i, N)] >= K && fact[i].size() > max)
            res = i, max = fact[i].size();
    }
    cout << res << endl;
}