lines = open("input.txt", "r").read().splitlines()
overlap = 0

for line in lines:
    lota, lotb = line.split(",")
    lota = [int(i) for i in lota.split("-")]
    lotb = [int(i) for i in lotb.split("-")]
    intersect = set(range(lota[0], lota[1] + 1)).intersection(
        set(range(lotb[0], lotb[1] + 1))
    )
    if len(intersect) > 0:
        overlap = overlap + 1
print(overlap)