coursera_week4_2

def IsPrime(n):

    i = 2
    nn = n ** .5
    while i<=nn:
        i += 1
        if n % i == 0 :
            break
            
    if i == nn:       
        return "YES"
    else:
        return "NO"


x = int(input())
print(IsPrime(x))


def IsPrime(n):
    nn = n ** .5
    i = 2
    while n % i != 0:
        i += 1
        if i > nn:
             break
    if i == n:
        IsPrime = "YES"
    else:
        IsPrime = "NO"
    return IsPrime


x = int(input())
print(IsPrime(x))