// yukicoder: No.811 約数の個数の最大化
// 2019.6.15 bal4u

#include <stdio.h>

#define MAX 100000
#define PMAX  65
int ptbl[PMAX+2] = {
	2,   3,   5,   7,  11,  13,  17,  19,  23,  29,
   31,  37,  41,  43,  47,  53,  59,  61,  67,  71,
   73,  79,  83,  89,  97, 101, 103, 107, 109, 113,
  127, 131, 137, 139, 149, 151, 157, 163, 167, 173,
  179, 181, 191, 193, 197, 199, 211, 223, 227, 229,
  233, 239, 241, 251, 257, 263, 269, 271, 277, 281,
  283, 293, 307, 311, 313 };

int base[PMAX], power[PMAX], sz;
int f[MAX+2], d[MAX+2];

int main()
{
	int i, j, k, n, N, K, max, idx;

	scanf("%d%d", &N, &K);
	
	// Nの素因数分解
	n = N;
	for (i = 0; n > 1 && i < PMAX; i++) {
		k = ptbl[i];
		if (n % k == 0) {
			base[sz] = k;
			do n /= k, power[sz]++;
			while (n % k == 0);
			sz++;
		}
	}
	if (n > 1) base[sz] = n, power[sz++] = 1;

	// 共通素因数
	for (i = 0; i < sz; i++) {
		j = base[i];
		for (k = 0; k < power[i]; k++) {
			for (n = j; n <= N; n += j) f[n]++;
			j *= base[i];
		}
	}
	
	// 約数の数
	max = 0;
	for (i = 2; i < N; i++) d[i] = 2;
	for (i = 2; i <= N/2; i++) {
		for (j = i << 1; j < N; j += i) {
			if (++d[j] > max && f[j] >= K) max = d[j], idx = j;
		}
	}
	printf("%d\n", idx);
	return 0;
}