#!/bin/python

import sys
def minimumNumber(n, p):
    sau = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
    cau = 0
    sa = 'abcdefghijklmnopqrstuvwxyz'
    ca = 0
    sn = '0123456789'
    cn = 0
    sc = '!@#$%^&*()-+'
    cc = 0
    
    
    ans = 0
    for i in range(26):
        if(sa[i] in p):
            ca+=1
    for i in range(10):
        if (sn[i] in p):
            cn+=1
    for i in range(26):
        if(sau[i] in p):
            cau+=1
    for i in range(len(sc)):
        if sc[i] in p:
            cc+=1
    ar = [ca,cn,cau,cc]
    if(len(p) >= 6):
        for i in range(4):
            if ar[i] == 0:
                ans +=1
        return ans
            
    else:
        bb = len(p)
        for i in range(4):
            if ar[i] == 0:
                ans+=1
        newlenbb = bb+ans
        if newlenbb >=6:
            return ans
        else:
            return ans+6-newlenbb

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