import bisect

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

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

print(len(dp))