hdoj：2037

#include <iostream>
using namespace std;
struct Time
{
    int start;
    int end;

};

Time times[];
int dp[];

void sortTimes(Time times[], int n)
{
    // 直接插入排序
    for (int i = ; i <= n; i++)
    {
        Time t = times[i];
        int j = i - ;
        while (j >=  && times[j].start > t.start)
        {
            times[j + ] = times[j];
            j--;
        }
        j++;
        times[j] = t;
    }
}
int main()
{
    int n;
    while (cin >> n && n != )
    {
        for (int i = ; i <= n; i++)
        {
            cin >> times[i].start >> times[i].end;
        }
        sortTimes(times,n);
        //cout << endl;
        //for (int i = 1; i <= n; i++)
        //{
            //cout<< times[i].start << " "<<times[i].end<<endl;
        //}

        // start 升序后，找到 start <= end  的最长序列长度
        int longest = -;
        dp[] = ;
        dp[] = ;
        for (int i = ; i <= n; i++)
        {
            dp[i] = ;
            int sublongest = ;
            for (int j = ; j < i; j++)
            {
                if (times[j].end <= times[i].start)
                {
                    sublongest = sublongest >= dp[j] ? sublongest : dp[j];
                }
            }
            sublongest += ;
            dp[i] = sublongest;
            longest = longest > dp[i] ? longest : dp[i];

        }
        cout << longest << endl;
    }
}