#include <stdio.h>
#include <vector>
#include <functional>
#include <algorithm>
#include <utility>

int main() {
    int n, k; scanf("%d%d", &n, &k);

    std::function<int (int)> countDivisor = [](int x) {
        int count = 0;
        for(int i = 1; i * i <= x; i++) {
            if(x % i) continue;
            count += 2;
            if(i * i == x) count--;
        }
        return count;
    };

    std::function<int (int, int)> countCommonFactor = [](int x, int y) {
        int g = std::__gcd(x, y);

        int count = 0;
        for(int i = 2; i * i <= g; i++) {
            if(g % i) continue;
            while(g % i == 0) {
                g /= i;
                count++;
            }
        }
        if(g != 1) count++;
        return count;
    };

    int ans = 0, ma = 0;
    for(int i = 1; i < n; i++) {
        if(countCommonFactor(i, n) < k) continue;
        int latte = countDivisor(i);
        if(latte > ma) {
            ma = latte;
            ans = i;
        }
    }
    printf("%d\n", ans);
    return 0;
}