#!/bin/python3

import sys
numbers = "0123456789"
lower_case = "abcdefghijklmnopqrstuvwxyz"
upper_case = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
special_characters = "!@#$%^&*()-+"
def minimumNumber(n, password):
    e,l,u,s=True,True,True,True
    for x in password:
        if x in numbers:
            e=False
        elif x in lower_case:
            l=False
        elif x in upper_case:
            u=False
        elif x in special_characters:
            s=False
    return max(e+l+u+s,6-n)
if __name__ == "__main__":
    n = int(input().strip())
    password = input().strip()
    answer = minimumNumber(n, password)
    print(answer)