import bisect

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

dp = []
for L, R in intervals:
    if not dp:
        dp.append(L)
    else:
        pos = bisect.bisect_left(dp, R)
        k_max = pos - 1
        if k_max >= 0:
            x = max(L, dp[k_max] + 1)
        else:
            x = L
        new_length = k_max + 2
        if new_length > len(dp):
            dp.append(x)
        else:
            if x < dp[new_length - 1]:
                dp[new_length - 1] = x

print(len(dp))