human
A prime number is a number which has exactly two distinct divisors: one and itself. For example, numbers 2, 7, 3 are prime, and 1, 6, 4 are not.

The next prime number after x is the smallest prime number greater than x. For example, the next prime number after 2 is 3, and the next prime number after 3 is 5. Note that there is exactly one next prime number after each number. So 5 is not the next prime number for 2.

One cold April morning Panoramix predicted that soon Kakofonix will break free from his straitjacket, and this will be a black day for the residents of the Gallic countryside.

Panoramix's prophecy tells that if some day Asterix and Obelix beat exactly x Roman soldiers, where x is a prime number, and next day they beat exactly y Roman soldiers, where y is the next prime number after x, then it's time to wait for Armageddon, for nothing can shut Kakofonix up while he sings his infernal song.

Yesterday the Gauls beat n Roman soldiers and it turned out that the number n was prime! Today their victims were a troop of m Romans (m > n). Determine whether the Gauls should wait for the black day after today's victory of Asterix and Obelix?

Input

The first and only input line contains two positive integers — n and m (2 ≤ n < m ≤ 50). It is guaranteed that n is prime.

Pretests contain all the cases with restrictions 2 ≤ n < m ≤ 4.

Output

Print YES, if m is the next prime number after n, or NO otherwise.

Examples

Input

3 5

Output

YES

Input

7 11

Output

YES

Input

7 9

Output

NO
Using python can you solve the prior task?
 ... Write me a Python program to determine whether the Gauls should wait for the black day after today's victory of Asterix and Obelix?
assistant
#Here is Python program to determine whether the Gauls should wait for the black day after today's victory of Asterix and Obelix.

class PanoramixPrediction:
    def solve(self, n, m):
        primes = []
        for x in range(1, 55):
            divs = []
            for y in range(1, x + 1):
                if x % y == 0:
                    divs.append(y)
            if len(divs) == 2 and 1 in divs and x in divs:
                primes.append(x)
        if m in primes and primes.index(m)==primes.index(n)+1:
            return "YES"
        else:
            return "NO"
if __name__ == "__main__":
    n, m = map(int, raw_input().split(" "))
    pp = PanoramixPrediction()
    print pp.solve(n, m)