meetings = [(1, 4), (3, 5), (0, 6), (5, 7), (3, 8), (5, 9), (6, 10), (8, 11), (8, 12), (2, 13), (12, 14)]

meetings.sort(key=lambda x: x[1])

count = 0
end_time = 0

for start,end in meetings:
    if start >= end_time:
        count += 1
        end_time = end

print(count)