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* &gt; *n*). Determine whether the Gauls should wait for the black day after today's victory of Asterix and Obelix?
The first and only input line contains two positive integers — *n* and *m* (2 ≤ *n* &lt; *m* ≤ 50). It is guaranteed that *n* is prime.

Pretests contain all the cases with restrictions 2 ≤ *n* &lt; *m* ≤ 4.
none
3 5
YES
7 11
YES
7 9
NO
2 3
YES
2 4
NO
3 4
NO
3 5
YES
5 7
YES
7 11
YES
11 13
YES
13 17
YES
17 19
YES
19 23
YES
23 29
YES
29 31
YES
31 37
YES
37 41
YES
41 43
YES
43 47
YES
2 5
NO
2 7
NO
2 6
NO
2 11
NO
3 6
NO
3 7
NO
3 9
NO
5 6
NO
5 9
NO
5 11
NO
5 13
NO
5 15
NO
7 8
NO
7 13
NO
13 15
NO
13 17
YES
19 21
NO
13 20
NO
41 49
NO
43 49
NO
47 50
NO
47 49
NO
47 48
NO
23 25
NO
2 50
NO
31 33
NO
l=[int(i) for i in input().split()];ll=[]
a=l[0];b=l[len(l)-1];c=0
for i in range(a,b+1):
    c=0
    for j in range(2,i):
        if i%j==0:
            c=1
    if c==0:
        ll.append(i)
if l==ll:
    print("YES")
else:
    print("NO")   