Guessing game with 5 chances in python [closed]

This is my code:

import random

letters = ['a','g','s','s','c','v','e','g','d','g']

random_letter = random.choice(letters)

guesses_left = 5
while guesses_left > 0:
  guess = input("Your guess: ")
  if guess == random_letter:
    print ("You win!")
    break
  guesses_left -= 1 
else:
  print ("You lose.")

My question: Why am I able to type other types than strings? For example, if I run the code and answer with an integer I don't get error. If this problem is not fixable, is there a better way to create this type of game?