import math

def isprime(n):
	if n == 1:
		return False
	else:
		for i in range(2, math.floor(math.sqrt(n))+1):
			if n % i == 0:
				return False
		return True

n = int(input())

if n == 1:
	print("NO")
else:
	print(["YES","NO"][isprime(n)])