Recently, Anton has found a set. The set consists of small English letters. Anton carefully wrote out all the letters from the set in one line, separated by a comma. He also added an opening curved bracket at the beginning of the line and a closing curved bracket at the end of the line. 

Unfortunately, from time to time Anton would forget writing some letter and write it again. He asks you to count the total number of distinct letters in his set.
The first and the single line contains the set of letters. The length of the line doesn't exceed 1000. It is guaranteed that the line starts from an opening curved bracket and ends with a closing curved bracket. Between them, small English letters are listed, separated by a comma. Each comma is followed by a space.
input_str = input().strip()
# 去掉字符串首尾的空格

if len(input_str) <= 2:
    # 如果字符串长度小于等于2，说明字符串里面没有有效字符
    print(0)
else:
    # 否则，把大括号和空格去掉，得到一个只包含小写字母的字符串
    input_str = input_str[1:-1].replace(' ', '')
    # 使用set数据结构统计不同字符的个数
    unique_chars = set(input_str)
    print(len(unique_chars))

				  	 	 	 		 	  		  		 	