import bisect

def main():
    import sys
    input = sys.stdin.read
    data = input().split()
    N = int(data[0])
    intervals = []
    index = 1
    for _ in range(N):
        L = int(data[index])
        R = int(data[index + 1])
        intervals.append((L, R))
        index += 2
    
    dp = []
    for L, R in intervals:
        k = bisect.bisect_left(dp, R)
        if k == 0:
            a = L
        else:
            a = max(L, dp[k-1] + 1)
        if a > R:
            continue
        if k < len(dp):
            if a < dp[k]:
                dp[k] = a
        else:
            dp.append(a)
    print(len(dp))

if __name__ == "__main__":
    main()