import bisect

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

dp = []
for L, R in intervals:
    # Find the largest index where dp[index] < R
    idx = bisect.bisect_left(dp, R)
    k = idx - 1
    if k == -1:
        x = L
    else:
        x = max(L, dp[k] + 1)
    # Determine the new length
    new_len = k + 2
    if new_len > len(dp):
        dp.append(x)
    else:
        if x < dp[new_len - 1]:
            dp[new_len - 1] = x

print(len(dp))