#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;
    }

    vector<int> ans;
    int K = 0;
    rep(i,500) {
        bool flag = false;
        rep(j,500) {
            if (grid[i][j] > 0) {
                ans.push_back(grid[i][j]);
                ++K;
                flag = true;
                j += 10;
            }
        }
        if (flag) {
            i += 10;
        }
    }
    cout << K << '\n';
    rep(i,K) {
        cout << ans[i] << ' ';
    }
    cout << '\n';
    return 0;
}