#!/bin/python

import sys

def minimumNumber(n, password):
    # Return the minimum number of characters to make the password strong
    
    aps = 4*[False]

    
    for i in range(n):
        
        if (password[i].isdigit()):
            aps[0] = True
        if (password[i].isupper()):
            aps[1] = True
        if (password[i].islower()):
            aps[2] = True
        if (password[i] == '!' or password[i] == '@' or password[i] == '#' or password[i] == '$' or password[i] == '%' or \
            password[i] == '^' or password[i] == '&' or password[i] == '*' or password[i] == '(' or password[i] == ')' or \
            password[i] == '-' or password[i] == '+'):
            aps[3] = True

    count = 0
    for i in range(4):
        if (not aps[i]):
            count += 1

    return max(count, 6-len(password))
    
    
if __name__ == "__main__":
    n = int(raw_input().strip())
    password = raw_input().strip()
    answer = minimumNumber(n, password)
    print answer