#!/bin/python3

import sys

numbers = "0123456789"
lower_case = "abcdefghijklmnopqrstuvwxyz"
upper_case = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
special_characters = "!@#$%^&*()-+"

def minimumNumber(n, password):
    tests = [False] * 4
    req = 4
    for c in password:
        if c in numbers and not tests[0]:
            tests[0] = True
            req -= 1
        elif c in lower_case and not tests[1]:
            tests[1] = True
            req -= 1
        elif c in upper_case and not tests[2]:
            tests[2] = True
            req -= 1
        elif c in special_characters and not tests[3]:
            tests[3] = True
            req -= 1
    minLen = 6 - len(password)
    if req > minLen:
        return req
    else:
        return minLen

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