#!/bin/python3

import sys

def minimumNumber(n, password):
    m = '0123456789'
    l = 'abcdefghijklmnopqrstuvwxyz'
    u = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
    s = '!@#$%^&*()-+'
    (a,b,c,d)=(0,0,0,0)
    for x in password:
        if x in m:
            a=1
        elif x in l:
            b=1
        elif x in u:
            c=1
        elif x in s:
            d=1
    y=4-(a+b+c+d)
    if n<6:
        if y>6-n:
            return y
        else:
            return 6-n
    else:
        return y
        

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