#!/bin/python

import sys

numbers = "0123456789"
lower_case = "abcdefghijklmnopqrstuvwxyz"
upper_case = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
special_characters = "!@#$%^&*()-+"

def minimumNumber(n, password):
    needsNumber = 1
    needsLower = 1
    needsUpper = 1
    needsSpec = 1
    for c in password:
        if c in numbers:
            needsNumber = 0
        if c in lower_case:
            needsLower = 0
        if c in upper_case:
            needsUpper = 0
        if c in special_characters:
            needsSpec = 0
    lenDiff = 6 - len(password)
    charDiff = sum([needsNumber, needsLower, needsUpper, needsSpec])
    return max([lenDiff, charDiff])
        

if __name__ == "__main__":
    n = int(raw_input().strip())
    password = raw_input().strip()
    answer = minimumNumber(n, password)
    print answer