#!/bin/python3

import sys

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


def minimumNumber(n, password):
    flags = 0
    for c in password:
        if c in special_characters:
            flags |= 1
        elif c in numbers:
            flags |= 2
        elif c in lower_case:
            flags |= 4
        else:
            flags |= 8
        if flags == 15:
            break
    ret = 0
    for i in range(4):
        if (1 << i) & flags == 0:
            ret += 1
    return max(6 - len(password), ret)

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