#include<iostream>
#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<string>
#include<queue>
#include<algorithm>
#include<map>
#include<iomanip>
#define INF 99999999
using namespace std;
const int MAX=1001;
int sum[MAX][2],**s;//sum[i][]记录以第i个元素为最后元素的最长子序列的长度和该元素前一个元素
bool cmp(int *a,int *b){
if(a[0] == b[0])return a[1]>b[1];
return a[0]<b[0];
}
void DFS_output(int i){
if(sum[i][1] == i){
cout<<s[i][2]+1<<endl;
return;
}
DFS_output(sum[i][1]);
cout<<s[i][2]+1<<endl;
}
int main(){
int n=0,k;
s=new int*[MAX];
for(int i=0;i<MAX;++i)s[i]=new int[3];
while(cin>>s[n][0]>>s[n][1]){s[n][2]=n;++n;}
sort(s,s+n,cmp);
for(int i=0;i<n;++i){
k=i;
for(int j=0;j<i;++j){
if(s[i][1]<s[j][1] && s[i][0]>s[j][0] && sum[j][0]>sum[k][0])k=j;
}
sum[i][0]=sum[k][0]+1;
sum[i][1]=k;
}
k=0;
for(int i=1;i<n;++i)if(sum[i][0]>sum[k][0])k=i;
cout<<sum[k][0]<<endl;
DFS_output(k);
return 0;
}
http://acm.hdu.edu.cn/showproblem.php?pid=1160