题解 | #素数判定#

#1不是质数
def iszs(n):
    for i in range(2, n):
        if n % i == 0:
            return False
    return True


n = int(input())
if iszs(n) and n != 1:
    print("yes")
elif n == 1:
    print("no")
else:
    print("no")