#  Part 1
with open("input.txt") as F:
    data = F.read().strip()
alpha = 'abcdefghijklmnopqrstuvwxyz'
search = []
for i in alpha:
    search.append(i + i.upper())
    search.append(i.upper() + i)

l = 0
while (len(data) != l):
    l = len(data)
    for term in search:
        data = data.replace(term, '')


print(len(data))