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.
Input
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.
Output
Print a single number — the number of distinct letters in Anton's set.