import bisect

def main():
    import sys
    input = sys.stdin.read
    data = input().split()
    idx = 0
    N = int(data[idx])
    idx += 1
    ranges = []
    for _ in range(N):
        L = int(data[idx])
        R = int(data[idx+1])
        ranges.append((L, R))
        idx += 2
    
    dp = []
    for L, R in ranges:
        if not dp:
            x = L
            dp.append(x)
        else:
            m = dp[-1]
            x_candidate = m + 1
            optimal_x = max(L, x_candidate)
            if optimal_x <= R:
                dp.append(optimal_x)
            else:
                x = L
                pos = bisect.bisect_left(dp, x)
                if pos < len(dp) and x < dp[pos]:
                    dp[pos] = x
                elif pos == 0:
                    dp[0] = x
    print(len(dp))

if __name__ == "__main__":
    main()