#!/usr/bin/env python3
import re
pattern = re.compile('(\d+)-(\d+)\s(\w):\s(\w+)')
with open('input', 'r') as f:
    content = list(map(str.strip, f.readlines()))

valid_pws = 0
for entry in content:
    p1, p2, char, pw = re.match(pattern, entry).groups(1)
    p1 = int(p1) - 1
    p2 = int(p2) - 1
    if pw[p1] == char and pw[p2] != char or pw[p1] != char and pw[p2] == char:
        valid_pws += 1
    

print(valid_pws)