Return to input if input is incorrect

Not sure how to return to input if the input is not a prime number until it is.

num = int(input("Enter a number: "))
flag = False
if num > 1:
    for i in range(2, num):
        if (num % i) == 0:
            flag = True
            break
if flag:
    print(num, "is not a prime number")
else:
    print(num, "is a prime number")

>Solution :

Wrap your code within while:

is_prime = False
while not is_prime:
    num = int(input("Enter a number: "))
    if num > 1:
        is_prime = True
        for i in range(2, num):
            if (num % i) == 0:
                is_prime = False
                break
    if is_prime:
        print(num, "is a prime number")
    else:
        print(num, "is not a prime number")