#!/bin/python3

import sys

def minimumNumber(n, p):
    # Return the minimum number of characters to make the password strong
    num = "0123456789"
    l = "abcdefghijklmnopqrstuvwxyz"
    u = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
    s = "!@#$%^&*()-+"
    nc,lc,uc,sc=0,0,0,0
    for v in p:
        if num.find(v)>=0:nc=1
        elif l.find(v)>=0:lc=1
        elif u.find(v)>=0:uc=1
        elif s.find(v)>=0:sc=1
    need=4-(nc+lc+uc+sc)
    return max(need,6-int(n))    

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