try:
    while True:
        # Read the dimensions of the square
        size = int(input("Tamaño: "))
        if size == 0:
            break
        if size > 0 and size <= 20:
            # For each line
            for row in range(size):
                # Print a line
                for column in range(size):
                    print("*", end="")
                print()
        else:
            print("Tamaño debe estar entre 1 y 20")
except ValueError:
    print("Tamaño inválido")