This program only makes an oriented graph and dfs it.

#include <stdio.h>
#include <vector>
using namespace std;

vector <int> v[500];
int d_[500],cm,cmp,totmax=0;
char c[500],c_[500];
short l[500],r[500],path[500];


void dfs(int ve,int d)
{
    c[ve]=1;
    c_[ve]=1;
    if(d>cm)
    {
        cm=d;
        cmp=ve;
    }
    int i;
    for(i=0;i<v[ve].size();i++)
    {
        if(!c[v[ve][i]])
        {
            d_[v[ve][i]]=ve+1;
            dfs(v[ve][i],d+1);
        }
    }
}
void swap()
{
    int p=cmp;
    for(int i=0;;i++,p=d_[p]-1)
    {
        path[i]=p+1;
        if(!d_[p])
            break;
    }
}

int main()
{
//    freopen("in","r",stdin);
    int n,i,j,tm1,tm2;
    scanf("%d",&n);
    for(i=0;i<n;i++)
    {
        scanf("%d%d",&tm1,&tm2);
        l[i]=tm1;
        r[i]=tm2;
        for(j=0;j<i;j++)
        {
            if(l[j]>l[i]&&r[j]<r[i])
                v[i].push_back(j);
            else if(l[j]<l[i]&&r[j]>r[i])
                v[j].push_back(i);
        }
    }
/*    for(i=0;i<n;i++)
    {
        for(j=0;j<v[i].size();j++)
            printf("%d ",v[i][j]);
        printf("\n");
    }*/
    for(i=0;i<n;i++)
        c_[i]=0;
    for(i=0;i<n;i++)
    {
        if(c_[i])
            continue;
        for(j=0;j<n;j++)
        {
            d_[j]=-1;
            c[j]=0;
        }
        d_[i]=0;
        cm=0;
        dfs(i,1);
        /*for(j=0;j<n;j++)
            printf("%d ",path[j]);
        printf("\n");*/
        if(cm>totmax)
        {
            totmax=cm;
            swap();
        }
    }
    printf("%d",totmax);
    for(i=0;i<totmax;i++)
        printf(" %d",path[i]);
    return 0;
}