import bisect

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

dp = []
for L, R in intervals:
    idx = bisect.bisect_left(dp, R) - 1
    if idx >= 0:
        candidate = max(dp[idx] + 1, L)
    else:
        candidate = L
    if candidate <= R:
        if idx + 1 < len(dp):
            if candidate < dp[idx + 1]:
                dp[idx + 1] = candidate
        else:
            dp.append(candidate)
print(len(dp))