#include <bits/stdc++.h>
#define rep(i,n) for (int i = 0; i < (int)(n); i ++)
#define irep(i,n) for (int i = (int)n - 1;i >= 0;--i)
using namespace std;
using ll = long long;
using PL = pair<ll,ll>;
using P = pair<int,int>;
constexpr int INF = 1000000000;
constexpr long long HINF = 1000000000000000;
constexpr long long MOD = 1000000007;// = 998244353;
constexpr double EPS = 1e-4;
constexpr double PI = 3.14159265358979;

int main() {
    int N; cin >> N;
    vector<vector<int>> grid(500,vector<int>(500,0));
    rep(i,N) {
        int x,y; cin >> x >> y;
        grid[x - 1][y - 1] = i + 1;
    }
    int K = 0;
    vector<int> ans;
    int ny = 0,nx = 0;
    while (K*90 < N) {
        bool flag = false;
        for (int y = ny;y < ny + 10;++y) {
            for (int x = nx; x < nx + 10;+x) {
                if (grid[y][x] > 0) {
                    ans.push_back(grid[y][x]);
                    flag = true;
                    ++K;
                    ny = y + 20;
                    if (ny > 500) {
                        ny = 0;
                        nx += 20;
                    }
                    break;
                }
            }
            if (flag) break;
        }
    }
    cout << K << '\n';
    rep(i,K) cout << ans[i] << ' ';
    cout << '\n';
    return 0;
}