def camelcase(text):
    new_text = [text[0].lower()]
    for char in text[1:]:
        if char in ('ABCDEFGHIJKLMNOPQRSTUVWXYZ'):
            new_text.append('_')
            new_text.append(char.lower())
        else:
            new_text.append(char)
     
    return ''.join(new_text)
    
def main():
    text = input("Write your text please: ")
    print(camelcase(text))

main()