import bisect

def main():
    import sys
    input = sys.stdin.read().split()
    idx = 0
    N = int(input[idx])
    idx += 1
    intervals = []
    for _ in range(N):
        L = int(input[idx])
        R = int(input[idx+1])
        intervals.append((L, R))
        idx += 2
    
    INF = 1 << 60
    dp = [-INF, INF]
    
    for L, R in intervals:
        k = bisect.bisect_left(dp, R) - 1
        if k < 0:
            continue
        new_val = max(L, dp[k] + 1)
        if new_val > R:
            continue
        if k + 1 < len(dp):
            if new_val < dp[k + 1]:
                dp[k + 1] = new_val
        else:
            dp.append(new_val)
    
    print(len(dp) - 1)

if __name__ == '__main__':
    main()