def isprime(input_number):
    isPrime = False
    for index in range (2, input_number):
        if (input_number % index) == 0:
            isPrime = False
            break
        else:
            isPrime = True
    return isPrime
target=1000000
for i in range(target, 2, -1):
    if isprime(i) == True:
        print(str(i))
        break