#!/bin/python3

import sys

numbers = "0123456789"
lower = "abcdefghijklmnopqrstuvwxyz"
upper = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
spec = "!@#$%^&*()-+"

def minimumNumber(n, password):
    criteriaLeft = 4
    needsNum, needsUp, needsLow, needsSpec = True, True, True, True
    for i in range(n):
        if needsNum:
            if password[i] in numbers:
                needsNum = False
                criteriaLeft -=1
        if needsUp:
            if password[i] in upper:
                needsUp = False
                criteriaLeft -=1
        if needsLow:
            if password[i] in lower:
                needsLow = False
                criteriaLeft -=1
        if needsSpec:
            if password[i] in spec:
                needsSpec = False
                criteriaLeft -=1
    return max(criteriaLeft, 6-n)
        

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