elves = []
count = 0

def inrange(lb, ub, check):
    """Returns true iff check is inclusive in-between lb and ub."""
    return check >= lb and check <= ub

with open("input.txt", "r") as f:
    for line in f.readlines():
        line = line.strip("\n")
        # Some python magic to split out the strings and convert them to integers
        pair = [x.split("-") for x in line.split(",")]
        pair = [[int(y) for y in x] for x in pair]
        elves.append(pair)
        # Elves is now a list of list of lists.
    for elf in elves:
        lb1 = elf[0][0]
        lb2 = elf[1][0]
        ub1 = elf[0][1]
        ub2 = elf[1][1]
        if (inrange(lb1, ub1, ub2) or
            inrange(lb1, ub1, lb2) or
            inrange(lb2, ub2, ub1) or
            inrange(lb2, ub2, lb1)):
            count += 1
print(count)