n=int(input())
s=input()
l=0
b=0
num=0
sp=0
for i in range(len(s)):
	if 97 <= ord(s[i]) <=122:
		l=1
	elif 65 <= ord(s[i]) <=90:
		b=1
	elif 48 <= ord(s[i]) <=57:
		num=1
	else:
		sp=1
if 4-(l+b+num+sp)+len(s)<6:
	print(6-len(s))
else:
	print(4-(l+b+num+sp))