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| #include <algorithm>
#include <iostream>
#include <cstring>
#include <cstdio>
#include <vector>
#include <queue>
using namespace std;
int n, f[50005];
vector<int> vec[50005];
struct Point{
int x, y, b1, b2, id;
}pt[50005];
namespace work1{
int liX[50005], liY[50005], liB1[50005], liB2[50005], cntLiX, cntLiY, cntLiB1, cntLiB2;
int oriX[50005], oriY[50005], bucX[50005], bucB1[50005], bucB2[50005], movU[50005];
int movL[50005], movR[50005], fUp[50005], gUp[50005], g[50005];
bool cmp1(Point a, Point b){
return a.y>b.y;
}
bool cmp2(Point a, Point b){
return a.x<b.x;
}
void liSanHua(){
for(int i=1; i<=n; i++){
liX[++cntLiX] = pt[i].x;
liY[++cntLiY] = pt[i].y;
pt[i].b1 = liB1[++cntLiB1] = pt[i].y - pt[i].x;
pt[i].b2 = liB2[++cntLiB2] = pt[i].x + pt[i].y;
pt[i].id = i;
}
sort(liX+1, liX+1+cntLiX);
sort(liY+1, liY+1+cntLiY);
sort(liB1+1, liB1+1+cntLiB1);
sort(liB2+1, liB2+1+cntLiB2);
cntLiX = unique(liX+1, liX+1+cntLiX) - liX - 1;
cntLiY = unique(liY+1, liY+1+cntLiY) - liY - 1;
cntLiB1 = unique(liB1+1, liB1+1+cntLiB1) - liB1 - 1;
cntLiB2 = unique(liB2+1, liB2+1+cntLiB2) - liB2 - 1;
for(int i=1; i<=n; i++){
pt[i].x = lower_bound(liX+1, liX+1+cntLiX, pt[i].x) - liX;
pt[i].y = lower_bound(liY+1, liY+1+cntLiY, pt[i].y) - liY;
oriX[i] = pt[i].x; oriY[i] = pt[i].y;
pt[i].b1 = lower_bound(liB1+1, liB1+1+cntLiB1, pt[i].b1) - liB1;
pt[i].b2 = lower_bound(liB2+1, liB2+1+cntLiB2, pt[i].b2) - liB2;
}
}
void preWork(){
sort(pt+1, pt+1+n, cmp1);
for(int i=1; i<=n; i++){
movU[pt[i].id] = bucX[pt[i].x];
movR[pt[i].id] = bucB1[pt[i].b1];
movL[pt[i].id] = bucB2[pt[i].b2];
bucX[pt[i].x] = bucB1[pt[i].b1] = bucB2[pt[i].b2] = pt[i].id;
}
sort(pt+1, pt+1+n, cmp2);
for(int i=1; i<=n; i++)
vec[pt[i].y].push_back(pt[i].id);
}
void trueWork(){
for(int y=cntLiY; y; y--){
int tmpMx=0, tmpId=0, sz=vec[y].size();
for(int i=0; i<sz; i++){
int x=vec[y][i];
if(movU[x] && f[movU[x]]>fUp[x]) fUp[x] = f[movU[x]], gUp[x] = movU[x];
if(movL[x] && f[movL[x]]>fUp[x]) fUp[x] = f[movL[x]], gUp[x] = movL[x];
if(movR[x] && f[movR[x]]>fUp[x]) fUp[x] = f[movR[x]], gUp[x] = movR[x];
f[x] = tmpMx; g[x] = tmpId;
if(tmpMx<sz-i+fUp[x]) tmpMx = sz - i + fUp[x], tmpId = x;
}
tmpMx = 0; tmpId = 0;
for(int i=sz-1; i>=0; i--){
int x=vec[y][i];
if(f[x]<fUp[x]+1) f[x] = fUp[x] + 1, g[x] = x;
if(f[x]<tmpMx) f[x] = tmpMx, g[x] = tmpId;
if(i+1+fUp[x]>tmpMx) tmpMx = i + 1 + fUp[x], tmpId = x;
}
}
}
void prt(int x){
int y=oriY[x], sz=vec[y].size(), nxt=g[x];
if(x!=n) printf("%d ", x);
if(oriX[nxt]<oriX[x]){
for(int i=0; i<sz; i++)
if(oriX[vec[y][i]]>oriX[x])
printf("%d ", vec[y][i]);
for(int i=sz-1; i>=0; i--)
if(oriX[vec[y][i]]<oriX[x] && oriX[vec[y][i]]>=oriX[nxt])
printf("%d ", vec[y][i]);
}
else if(oriX[nxt]>oriX[x]){
for(int i=sz-1; i>=0; i--)
if(oriX[vec[y][i]]<oriX[x])
printf("%d ", vec[y][i]);
for(int i=0; i<sz; i++)
if(oriX[vec[y][i]]>oriX[x] && oriX[vec[y][i]]<=oriX[nxt])
printf("%d ", vec[y][i]);
}
if(gUp[nxt]) prt(gUp[nxt]);
}
void main(){
liSanHua();
preWork();
trueWork();
printf("%d\n", f[n]-1);
prt(n);
}
}
namespace work2{
int hea[50005], cnt, du[50005], ss, tt, ans, cur[50005], lev[50005];
const int oo=0x3f3f3f3f;
bool isOk[50005];
queue<int> d;
struct Edge{
int too, nxt, val;
}edge[5000005];
void add_edge(int fro, int too, int val){
edge[cnt].nxt = hea[fro];
edge[cnt].too = too;
edge[cnt].val = val;
hea[fro] = cnt++;
}
void addEdge(int fro, int too, int val){
add_edge(fro, too, val);
add_edge(too, fro, 0);
}
void addEDGE(int fro, int too){
for(int i=hea[fro]; i!=-1; i=edge[i].nxt)
if(edge[i].too==too)
return ;
du[too]++; du[fro]--; isOk[too] = true;
addEdge(fro, too, oo);
}
void calc(int a, int b){
int sz=vec[a].size(), x=vec[a][b];
for(int i=0; i<b; i++){
int k=vec[a][i];
if(work1::movU[k] && f[work1::movU[k]]+sz-i==f[x]) addEDGE(k, work1::movU[k]);
if(work1::movL[k] && f[work1::movL[k]]+sz-i==f[x]) addEDGE(k, work1::movL[k]);
if(work1::movR[k] && f[work1::movR[k]]+sz-i==f[x]) addEDGE(k, work1::movR[k]);
}
for(int i=b+1; i<sz; i++){
int k=vec[a][i];
if(work1::movU[k] && f[work1::movU[k]]+i+1==f[x]) addEDGE(k, work1::movU[k]);
if(work1::movL[k] && f[work1::movL[k]]+i+1==f[x]) addEDGE(k, work1::movL[k]);
if(work1::movR[k] && f[work1::movR[k]]+i+1==f[x]) addEDGE(k, work1::movR[k]);
}
if(work1::movU[x] && f[work1::movU[x]]+1==f[x]) addEDGE(x, work1::movU[x]);
if(work1::movL[x] && f[work1::movL[x]]+1==f[x]) addEDGE(x, work1::movL[x]);
if(work1::movR[x] && f[work1::movR[x]]+1==f[x]) addEDGE(x, work1::movR[x]);
}
void build(){
memset(hea, -1, sizeof(hea));
isOk[n] = true;
for(int i=1; i<=work1::cntLiY; i++)
for(int j=0; j<vec[i].size(); j++)
if(isOk[vec[i][j]])
calc(i, j);
ss = n + 1; tt = n + 2;
for(int i=1; i<=n; i++)
if(du[i]>0) addEdge(ss, i, du[i]), ans += du[i];
else if(du[i]<0) addEdge(i, tt, -du[i]);
}
bool bfs(){
memset(lev, 0, sizeof(lev));
d.push(ss);
lev[ss] = 1;
while(!d.empty()){
int x=d.front();
d.pop();
for(int i=hea[x]; i!=-1; i=edge[i].nxt){
int t=edge[i].too;
if(!lev[t] && edge[i].val>0){
d.push(t);
lev[t] = lev[x] + 1;
}
}
}
return lev[tt]!=0;
}
int dfs(int x, int lim){
if(x==tt) return lim;
int addFlow=0;
for(int &i=cur[x]; i!=-1; i=edge[i].nxt){
int t=edge[i].too;
if(lev[t]==lev[x]+1 && edge[i].val>0){
int tmp=dfs(t, min(lim-addFlow, edge[i].val));
addFlow += tmp;
edge[i].val -= tmp;
edge[i^1].val += tmp;
if(addFlow==lim) break;
}
}
return addFlow;
}
void main(){
build();
while(bfs()){
for(int i=1; i<=tt; i++) cur[i] = hea[i];
ans -= dfs(ss, oo);
}
cout<<endl<<ans<<endl;
}
}
int main(){
cin>>n;
for(int i=1; i<=n; i++)
scanf("%d %d", &pt[i].x, &pt[i].y);
n++;
work1::main();
work2::main();
return 0;
}
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