def print_line(column_count):
    for column in range(column_count):
        print("*", end="")
    print()

def print_square(size):
    # For each line
    for row in range(size):
        # Print a line
        print_line(size)

def main():
    while True:
        try:
            # Read the dimensions of the square
            size = int(input("Tamaño: "))
            if size == 0:
                break
            if size > 0 and size <= 20:
                print_square(size)
            else:
                print("Tamaño debe estar entre 1 y 20")
        except ValueError:
            print("Tamaño inválido")

main()