import math

n, m = map(int, input().split())

def get_divisors(n):
    divisors = set()
    for i in range(1, int(math.isqrt(n)) + 1):
        if n % i == 0:
            divisors.add(i)
            divisors.add(n // i)
    return sorted(divisors)

divisors = get_divisors(n)
divisors_set = set(divisors)

possible_ds = []

for d in divisors:
    if d == n:
        if d <= m:
            possible_ds.append(d)
    else:
        if (n - d) in divisors_set and d <= m:
            possible_ds.append(d)

if not possible_ds:
    print(-1)
else:
    max_d = max(possible_ds)
    print(n // max_d)