"""
Write a Python program that outputs all possible strings formed by using the characters 'c', 'a', 't', 'd', 'o', and 'g'
exactly once.
"""

def permute(char_pool, current_str):
    if len(char_pool) == 0:
        print((current_str))
        return
    for i in range(len(char_pool)):
        permute(char_pool[:i] + char_pool[i+1:], current_str + char_pool[i])
    

permute('catdog', '')