#!/bin/python3

import sys

def minimumNumber(n, password):
    
    numbers = "0123456789"
    lower_case = "abcdefghijklmnopqrstuvwxyz"
    upper_case = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
    special_characters = "!@#$%^&*()-+"
    
    test1 = False
    test2 = False
    test3 = False
    test4 = False
    
    for c in password:
        if c in numbers:
            test1 = True
        elif c in lower_case:
            test2 = True
        elif c in upper_case:
            test3 = True
        elif c in special_characters:
            test4 = True
    needed = 0
    if not test1:
        needed += 1
    if not test2:
        needed += 1
    if not test3:
        needed += 1
    if not test4:
        needed += 1
    if (6 - n < needed):
        return needed
    else:
        return 6 - n


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