#!/bin/python3

import sys

s=[]
s.append(set("0123456789"))
s.append(set("ABCDEFGHIJKLMNOPQRSTUVWXYZ"))
s.append(set("abcdefghijklmnopqrstuvwxyz"))
s.append(set("!@#$%^&*()-+"))


def minimumNumber(n, password):
    symbs = set(password)
    missing = 0
    for si in s:
        missing += not (symbs & si)
    return max(missing,6-len(password))

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