Python 查找字符串中第一个只出现一次的字符

def find_first_non_repeating_char(s):
    char_counts = {}
    for char in s:
        if char in char_counts:
            char_counts[char] += 1
        else:
            char_counts[char] = 1
    for char in s:
        if char_counts[char] == 1:
            return char
    return 'No'

s = input()
print(find_first_non_repeating_char(s))