import math

def eh_primo(n):
    if n == 1:
        eh_primo = False
    elif n != 2 and n % 2 == 0:
        eh_primo = False
    else:
        eh_primo = True
        raiz = int(math.sqrt(n))
        for i in range(3, raiz+1, 2):
            if n % i == 0:
                eh_primo = False
                break
    return eh_primo

n, m = [int(x) for x in input().split()]

p1 = n
while not eh_primo(p1):
    p1 -= 1
    
p2 = m
while not eh_primo(p2):
    p2 += 1
    
print(p1*p2)