def prime(n):
  
    isprime = True

    if n<2:

        isprime = False

    else:

        for i in range(2,n):

            if n%i==0:

                isprime = False

                break

    return isprime

n = int(input('Enter a number: '))
flag, i = True, 1

if prime(n):

    print('Closest prime number =',n)

else:

    while flag:

        if prime(n+i) and prime(n-i):

            print(n-i,'and',n+i,'are closest prime numbers')

            flag = False

        elif prime(n-i):

            print('Closest prime number =',n-i)

            flag = False

        elif prime(n+i):

            print('Closest prime number =',n+i)

            flag = False

        i += 1