#!/bin/python

import sys

def minimumNumber(n, p):
    nm = "0123456789"
    lc = "abcdefghijklmnopqrstuvwxyz"
    uc = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
    sc = "!@#$%^&*()-+"
    
    c = 0
    a = 0
    b = 0
    d = 0
    for i in range(n):
        if p[i] in nm:
            a = 1
        if p[i] in lc:
            b = 1
        if p[i] in uc:
            c = 1
        if p[i] in sc:
            d = 1
        if a+b+c+d==4:
            if n>5:
                return 0
            else:
                return 6-n
    return max(6-n,4-(a+b+c+d))
    

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