#!/usr/bin/env python3

# Advent Of Code 2020 - Day 2

"""
1-5 k: kkkkhkkkkkkkkkk
5-7 k: blkqhtxfgktdkxzkksk
"""

filename = "input.txt"

def logical_xor(str1, str2):
    return bool(str1) ^ bool(str2)

with open(filename) as f:
    content = f.readlines()
#content = [x.strip() for x in content] 

validPasswords = 0

for i in content:
    line = i.split()
    
    pos1 = int(line[0].split("-")[0])-1
    pos2 = int(line[0].split("-")[1])-1

    character = line[1].rstrip(":")

    password = line[2]
    p1 = password[pos1]
    p2 = password[pos2]

# (a and not b) or (not a and b)

    if ( (p1 == character) and (p2 != character) ) or ( (p1 != character) and (p2 == character) ):
            validPasswords = validPasswords + 1
        

print (validPasswords)