from string import ascii_uppercase as up, ascii_lowercase as low, digits

spec=list('!@#$%^&*()-+')
up=list(up)
low=list(low)
dig=list(digits)

ac=0

l=int(input())
s=input()

dct={'up':0,'low':0,'digits':0,'special':0}

for c in s:
	if(c in up):
		dct['up']+=1
	elif(c in low):
		dct['low']+=1
	elif(c in dig):
		dct['digits']+=1
	else:
		dct['special']+=1

for Type in dct.keys():
	if(dct[Type]==0):
		ac+=1

if((l+ac)<6):
	ac+=6-(l+ac)

print(ac)