def print_duplicate_characters(string):
    duplicates = []
    for char in string:
        if string.count(char) > 1 and char not in duplicates:
            duplicates.append(char)
    return duplicates

# Example usage:
text = input("Enter a string: ")
duplicate_chars = print_duplicate_characters(text)
if duplicate_chars:
    print(f"The duplicate characters in the string are: {duplicate_chars}")
else:
    print("No duplicate characters found in the string.")