#!/bin/python

import sys

def minimumNumber(n, pa):
    numbers = "0123456789"
    lower_case = "abcdefghijklmnopqrstuvwxyz"
    upper_case = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
    special_characters = "!@#$%^&*()-+"
    p=0
    q=0
    r=0
    s=0
    for i in range(len(pa)):
        if(pa[i] in numbers):
            p+=1
        elif(pa[i] in lower_case):
            q+=1
        elif(pa[i] in upper_case):
            r+=1
        elif(pa[i] in special_characters):
            s+=1    
    if( len(pa)>=6) :
        t=0
        if(p<1): 
             t+=1
        if(q<1):
             t+=1
        if(r<1):
             t+=1    
        if(s<1):
             t+=1
        return t
    else:
        t=0
        
        if(p<1): 
             t+=1
        if(q<1):
             t+=1
        if(r<1):
             t+=1    
        if(s<1):
             t+=1
        if((t+len(pa))<6):
            return 6-len(pa)
        elif((t+len(pa))>=6):
            return t
if __name__ == "__main__":
    n = int(raw_input().strip())
    pa = raw_input().strip()
    answer = minimumNumber(n, pa)
    print answer