#include<bits/stdc++.h>
using namespace std;
#define int long long
#define REP(i,m,n) for(int i=(m);i<(n);i++)
#define rep(i,n) REP(i,0,n)
#define pb push_back
#define all(a) a.begin(),a.end()
#define rall(c) (c).rbegin(),(c).rend()
#define mp make_pair
#define endl '\n'
#define vec vector<ll>
#define mat vector<vector<ll> >
#define fi first
#define se second
typedef long long ll;
typedef pair<ll,ll> pll;
typedef long double ld;
const ll inf=1e9+7;
const ll mod=998244353;
int dx[]={0,1,0,-1};
int dy[]={1,0,-1,0};
signed main(){
    ll n;cin>>n;
    vector<vector<ll> >a(500,vector<ll>(500));
    rep(i,n){
        ll x,y;cin>>x>>y;
        x--;y--;
        a[x][y]=i+1;
    }
    vector<vector<ll> >used(500,vector<ll>(500));
    vector<ll>ans1(0);
    vector<ll>ans2(0);
    vector<ll>ans3(0);
    vector<ll>ans4(0);
    ll s=(n-1)/90+1;
    rep(i,500){
        rep(j,500){
            if(used[i][j])continue;
            if(a[i][j]==0)continue;
            ans1.pb(a[i][j]);
            used[i][j]=1;
            queue<pll>q;
            q.push(mp(i,j));
            while(!q.empty()){
                pll k=q.front();
                q.pop();
                ll x=k.first;
                ll y=k.second;
                rep(l,4){
                    ll nx=x+dx[l];
                    ll ny=y+dy[l];
                    if(nx<0||nx>=500||ny<0||ny>=500)continue;
                    if((nx-i)*(nx-i)+(ny-j)*(ny-j)>=100)continue;
                    if(used[nx][ny])continue;
                    q.push(mp(nx,ny));
                    used[nx][ny]=1;
                }
            }
        }
    }
    rep(i,500){
        rep(j,500)used[i][j]=0;
    }
    rep(j,500){
        rep(i,500){
            if(used[i][j])continue;
            if(a[i][j]==0)continue;
            ans2.pb(a[i][j]);
            used[i][j]=1;
            queue<pll>q;
            q.push(mp(i,j));
            while(!q.empty()){
                pll k=q.front();
                q.pop();
                ll x=k.first;
                ll y=k.second;
                rep(l,4){
                    ll nx=x+dx[l];
                    ll ny=y+dy[l];
                    if(nx<0||nx>=500||ny<0||ny>=500)continue;
                    if((nx-i)*(nx-i)+(ny-j)*(ny-j)>=100)continue;
                    if(used[nx][ny])continue;
                    q.push(mp(nx,ny));
                    used[nx][ny]=1;
                }
            }
        }
    }
    rep(i,500){
        rep(j,500)used[i][j]=0;
    }
    for(int i=499;i>=0;i--){
        for(int j=499;j>=0;j--){
            if(used[i][j])continue;
            if(a[i][j]==0)continue;
            ans3.pb(a[i][j]);
            used[i][j]=1;
            queue<pll>q;
            q.push(mp(i,j));
            while(!q.empty()){
                pll k=q.front();
                q.pop();
                ll x=k.first;
                ll y=k.second;
                rep(l,4){
                    ll nx=x+dx[l];
                    ll ny=y+dy[l];
                    if(nx<0||nx>=500||ny<0||ny>=500)continue;
                    if((nx-i)*(nx-i)+(ny-j)*(ny-j)>=100)continue;
                    if(used[nx][ny])continue;
                    q.push(mp(nx,ny));
                    used[nx][ny]=1;
                }
            }
        }
    }
    rep(i,500){
        rep(j,500)used[i][j]=0;
    }
    for(int j=499;j>=0;j--){
        for(int i=499;i>=0;i--){
            if(used[i][j])continue;
            if(a[i][j]==0)continue;
            ans4.pb(a[i][j]);
            used[i][j]=1;
            queue<pll>q;
            q.push(mp(i,j));
            while(!q.empty()){
                pll k=q.front();
                q.pop();
                ll x=k.first;
                ll y=k.second;
                rep(l,4){
                    ll nx=x+dx[l];
                    ll ny=y+dy[l];
                    if(nx<0||nx>=500||ny<0||ny>=500)continue;
                    if((nx-i)*(nx-i)+(ny-j)*(ny-j)>=100)continue;
                    if(used[nx][ny])continue;
                    q.push(mp(nx,ny));
                    used[nx][ny]=1;
                }
            }
        }
    }
    vector<ll>ans11(0);
    vector<ll>ans21(0);
    vector<ll>ans31(0);
    vector<ll>ans41(0);
    rep(i,500){
        rep(j,500)used[i][j]=0;
    }
    rep(i,500){
        for(int j=499;j>=0;j--){
            if(used[i][j])continue;
            if(a[i][j]==0)continue;
            ans11.pb(a[i][j]);
            used[i][j]=1;
            queue<pll>q;
            q.push(mp(i,j));
            while(!q.empty()){
                pll k=q.front();
                q.pop();
                ll x=k.first;
                ll y=k.second;
                rep(l,4){
                    ll nx=x+dx[l];
                    ll ny=y+dy[l];
                    if(nx<0||nx>=500||ny<0||ny>=500)continue;
                    if((nx-i)*(nx-i)+(ny-j)*(ny-j)>=100)continue;
                    if(used[nx][ny])continue;
                    q.push(mp(nx,ny));
                    used[nx][ny]=1;
                }
            }
        }
    }
    rep(i,500){
        rep(j,500)used[i][j]=0;
    }
    rep(j,500){
        for(int i=499;i>=0;i--){
            if(used[i][j])continue;
            if(a[i][j]==0)continue;
            ans21.pb(a[i][j]);
            used[i][j]=1;
            queue<pll>q;
            q.push(mp(i,j));
            while(!q.empty()){
                pll k=q.front();
                q.pop();
                ll x=k.first;
                ll y=k.second;
                rep(l,4){
                    ll nx=x+dx[l];
                    ll ny=y+dy[l];
                    if(nx<0||nx>=500||ny<0||ny>=500)continue;
                    if((nx-i)*(nx-i)+(ny-j)*(ny-j)>=100)continue;
                    if(used[nx][ny])continue;
                    q.push(mp(nx,ny));
                    used[nx][ny]=1;
                }
            }
        }
    }
    rep(i,500){
        rep(j,500)used[i][j]=0;
    }
    for(int i=499;i>=0;i--){
        rep(j,500){
            if(used[i][j])continue;
            if(a[i][j]==0)continue;
            ans31.pb(a[i][j]);
            used[i][j]=1;
            queue<pll>q;
            q.push(mp(i,j));
            while(!q.empty()){
                pll k=q.front();
                q.pop();
                ll x=k.first;
                ll y=k.second;
                rep(l,4){
                    ll nx=x+dx[l];
                    ll ny=y+dy[l];
                    if(nx<0||nx>=500||ny<0||ny>=500)continue;
                    if((nx-i)*(nx-i)+(ny-j)*(ny-j)>=100)continue;
                    if(used[nx][ny])continue;
                    q.push(mp(nx,ny));
                    used[nx][ny]=1;
                }
            }
        }
    }
    rep(i,500){
        rep(j,500)used[i][j]=0;
    }
    for(int j=499;j>=0;j--){
        rep(i,500){
            if(used[i][j])continue;
            if(a[i][j]==0)continue;
            ans41.pb(a[i][j]);
            used[i][j]=1;
            queue<pll>q;
            q.push(mp(i,j));
            while(!q.empty()){
                pll k=q.front();
                q.pop();
                ll x=k.first;
                ll y=k.second;
                rep(l,4){
                    ll nx=x+dx[l];
                    ll ny=y+dy[l];
                    if(nx<0||nx>=500||ny<0||ny>=500)continue;
                    if((nx-i)*(nx-i)+(ny-j)*(ny-j)>=100)continue;
                    if(used[nx][ny])continue;
                    q.push(mp(nx,ny));
                    used[nx][ny]=1;
                }
            }
        }
    }
    cout<<s<<endl;
    if(ans1.size()>=s){
        rep(i,s){
            cout<<ans1[i]<<' ';
        }
    }else if(ans2.size()>=s){
        rep(i,s){
            cout<<ans2[i]<<' ';
        }
    }else if(ans3.size()>=s){
        rep(i,s){
            cout<<ans3[i]<<' ';
        }
    }else if(ans4.size()>=s){
        rep(i,s){
            cout<<ans4[i]<<' ';
        }
    }else if(ans11.size()>=s){
        rep(i,s){
            cout<<ans11[i]<<' ';
        }
    }else if(ans21.size()>=s){
        rep(i,s){
            cout<<ans21[i]<<' ';
        }
    }else if(ans31.size()>=s){
        rep(i,s){
            cout<<ans31[i]<<' ';
        }
    }else if(ans41.size()>=s){
        rep(i,s){
            cout<<ans41[i]<<' ';
        }
    }else{
        if(n>=10000){
            cout<<1/0<<endl;
        }
    }
    cout<<endl;
}