input = open("./input.txt", "r")

total = 0

for line in input:
  trimmedLine = line.replace("\n", "")
  elves = trimmedLine.split(",")
  elf1 = elves[0].split("-")
  elf2 = elves[1].split("-")
  if (int(elf1[0]) <= int(elf2[0]) and int(elf1[1]) >= int(elf2[1])):
    total += 1
  elif (int(elf2[0]) <= int(elf1[0]) and int(elf2[1]) >= int(elf1[1])):
    total += 1

print(total)