Python-Strange response behavior in output

strings = input().replace(' ', '')
count = {}

for string in strings:
    count[string] = count.get(string, 0) + 1
leather = '\n'.join({f'{letter} -> {num}' for letter, num in count.items()})
print(leather)

# input = text
# correct answer = t -> 2 e -> 1 x -> 1
# wrong answer 80 percent in case = e -> 1 x -> 1 t -> 2