#import sys

while True:
    try:
        s = input()
        a_set = set() #使用集合去重特性
        for a in s:
            if 0 <= ord(a) < 128: #字符转ascii码ord. ascii码转字符chr
                a_set.add(a)

        print(len(a_set))
    except:
        #print(sys.exc_info())
        break