def is_prime(n:int):
    if n == 2:
        return True
    if n < 2 or n % 2 == 0:
        return False
    c = 0
    for i in range(3,c * c + 1,2):
        c = i
        if n % i == 0:
            return False
    return True

def is_same_backwards(n:str):
    for i in range(0,len(n) - 1,1):
        if n[i] != n[(i + 1) * -1]:
            return False
    return True

max = int(input());sum = 1
for i in range(11,max + 1,1):
    if is_prime(max) and is_same_backwards(str(max)):
        sum += 1
print(sum)

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