#!/usr/bin/env python

import string

ans_yes = 0
with open("input01.txt","r") as f:
	answers = set(string.ascii_lowercase)
	for line in f:
		line = line.strip()
		if len(line) == 0:
			ans_yes += len(answers)
			answers = set(string.ascii_lowercase)
			continue
		answers = answers.intersection(set(line))

ans_yes += len(answers)
print(ans_yes)