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

預測下一個數(shù)字是否是素數(shù)，其中包含2個意思，1：如果2個數(shù)字中間有素數(shù)，則一定不符合條件，2：如果第2個數(shù)字不是素數(shù)，也肯定不符合條件，將這兩個條件排除，剩下的就是符合要求的，下面是代碼：