题解 | #字符个数统计#

import sys

input_data = sys.stdin.read().strip()

def count_unique_characters(s):
    uni_str = set()
    for i in s:
        asc_code = ord(i)
        if 0 < asc_code < 127:
            uni_str.add(i)
    return len(uni_str)

result = count_unique_characters(input_data)
print(result)