#!/bin/python3

import sys

def minimumNumber(n, password):
    numbers = "0123456789"
    lower_case = "abcdefghijklmnopqrstuvwxyz"
    upper_case = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
    special_characters = "!@#$%^&*()-+"
    done = [0]*5
    done[4] = max(6 - n, 0)
    for p in password:
        if p in numbers:
            done[0] = 1
        if p in lower_case:
            done[1] = 1
        if p in upper_case:
            done[2] = 1
        if p in special_characters :
            done[3] = 1
    return max(4 - sum(done[0:4]), done[4])

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