import bisect

n = int(input())
intervals = [tuple(map(int, input().split())) for _ in range(n)]

tails = []

for L, R in intervals:
    idx = bisect.bisect_left(tails, R)
    j = idx - 1
    if j >= 0:
        current = tails[j] + 1
    else:
        current = L
    x = max(current, L)
    if x > R:
        continue
    if j + 1 < len(tails):
        if x < tails[j+1]:
            tails[j+1] = x
    else:
        tails.append(x)

print(len(tails))