import bisect

n = int(input())
intervals = []
for _ in range(n):
    L, R = map(int, input().split())
    intervals.append((L, R))

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

print(len(tails))