ural 1078 Segments

// ural 1078. Segments
// wa ac 0.031s
#include <iostream>
#include <string>
#include <cstdio>
#include <cstring>
#include <algorithm>
#include <cmath>
using namespace std;

#define FOR(i,a,b) for(i = (a); i < (b); ++i)
#define FORE(i,a,b) for(i = (a); i <= (b); ++i)
#define FORDE(i,a,b) for(i = (a); i >= (b); --i)

const int MAXN = 510;
const int INF = 0x7f7f7f7f;

int n;
int dp[MAXN], ed[MAXN];
struct node {
int x, y, i;
}p[MAXN];

int cmp(node a, node b) {
return (a.y - a.x) < (b.y - b.x);
}

void solve() {
int i, j;

scanf("%d", &n);
FORE(i, 1, n) {
scanf("%d %d", &p[i].x, &p[i].y);
p[i].i = i;
}
sort(p + 1, p + n + 1, cmp);
FORE(i, 1, n)
dp[i] = 1;
FORE(i, 2, n) FORE(j, 1, i - 1)
if(p[i].x < p[j].x && p[i].y > p[j].y)
dp[i] = max(dp[i], dp[j] + 1);
int maxx = -INF, maxi = -1;
FORE(i, 1, n)
if(maxx < dp[i])
maxx = dp[i], maxi = i;
i = maxi - 1;
int t = maxi;
int cnt = 0;
ed[cnt++] = p[t].i;
while(i >= 1) {
while(!(dp[i] == dp[t] - 1 && (p[i].x > p[t].x && p[i].y < p[t].y))) {
--i;
}
if(i < 1)
break;
ed[cnt++] = p[i].i;
t = i--;
}
printf("%d\n", cnt);
FORDE(i, cnt - 1, 0)
(i == cnt - 1) ? printf("%d", ed[i]) : printf(" %d", ed[i]);
cout<<endl;
}

int main() {
solve();
return 0;
}