Problem Description

FatMouse believes that the fatter a mouse is, the faster it runs. To disprove this, you want to take the data on a collection of mice and put as large a subset of this data as possible into a sequence so that the weights are increasing, but the speeds are decreasing.

 

Input

Input contains data for a bunch of mice, one mouse per line, terminated by end of file.

The data for a particular mouse will consist of a pair of integers: the first representing its size in grams and the second representing its speed in centimeters per second. Both integers are between 1 and 10000. The data in each test case will contain information for at most 1000 mice.

Two mice may have the same weight, the same speed, or even the same weight and speed.

 

Output

Your program should output a sequence of lines of data; the first line should contain a number n; the remaining n lines should each contain a single positive integer (each one representing a mouse). If these n integers are m[1], m[2],..., m[n] then it must be the case that

W[m[1]] < W[m[2]] < ... < W[m[n]]

and

S[m[1]] > S[m[2]] > ... > S[m[n]]

In order for the answer to be correct, n should be as large as possible.
All inequalities are strict: weights must be strictly increasing, and speeds must be strictly decreasing. There may be many correct outputs for a given input, your program only needs to find one.

 

Sample Input

 

Sample Output

 

#include <stdio.h>

#include <bits/stdc++.h>

using namespace std;

#define INF 0x3f3f3f3f

#define CLR(arr,val) memset(arr,val,sizeof(arr))

#define LC(x) (x<<1)

#define RC(x) ((x<<1)+1)

#define MID(x,y) ((x+y)>>1)

typedef pair<int,int> pii;

typedef long long LL;

const double PI=acos(-1.0);

const int N=1010;

struct info

{

    int speed;

    int weight;

    int pre;

    int id;

    bool operator<(const info &t)const

    {

        return (weight>t.weight||(weight==t.weight&&speed<t.speed));

    }

};

info arr[N];

int dp[N];

int main(void)

{

    int w,s,i,j;

    int cnt=0;

    while (~scanf("%d%d",&w,&s))

    {

        arr[cnt].id=cnt+1;

        arr[cnt].pre=-1;

        arr[cnt].weight=w;

        arr[cnt].speed=s;

        ++cnt;

    }

    sort(arr,arr+cnt);

    CLR(dp,0);

    for (i=0; i<cnt; ++i)

    {

        int tpre=-1;

        int pre_max=0;

        for (j=0; j<i; ++j)

        {

            if(dp[j]>pre_max&&arr[j].speed<arr[i].speed&&arr[j].weight>arr[i].weight)

            {

                pre_max=dp[j];

                tpre=j;

            }

            dp[i]=pre_max+1;

            arr[i].pre=tpre;

        }

    }

    int indx=max_element(dp,dp+cnt)-dp;

    queue<int>pos;

    while (indx!=-1)

    {

        pos.push(arr[indx].id);

        indx=arr[indx].pre;

    }

    printf("%d\n",pos.size());

    while (!pos.empty())

    {

        printf("%d\n",pos.front());

        pos.pop();

    }

    return 0;

}