#!/bin/python3

import sys

def minimumNumber(n, password):
    numbers = "0123456789"
    lower_case = "abcdefghijklmnopqrstuvwxyz"
    upper_case = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
    special_characters = "!@#$%^&*()-+"
    c1, c2, c3, c4 = 0, 0, 0, 0
    for c in password:
        c1 += 1 if c in numbers else 0
        c2 += 1 if c in lower_case else 0
        c3 += 1 if c in upper_case else 0
        c4 += 1 if c in special_characters else 0
    count = 0
    count += 1 if c1 > 0 else 0
    count += 1 if c2 > 0 else 0
    count += 1 if c3 > 0 else 0
    count += 1 if c4 > 0 else 0
    a1 = max(0, 4 - count)
    diff = max(0, 6 - len(password))
    return max(a1, diff)

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