#include <bits/stdc++.h>
using namespace std;
int main(){
  int N;
  cin >> N;
  vector<int> X(N), Y(N);
  for (int i = 0; i < N; i++){
    cin >> X[i] >> Y[i];
  }
  vector<vector<int>> group(90);
  for (int i = 0; i < N; i++){
    X[i] %= 10;
    Y[i] %= 18;
    int g = 0;
    if (X[i] >= 5){
      g ^= 45;
      X[i] -= 5;
    }
    if (Y[i] >= 9){
      g ^= 45;
      Y[i] -= 9;
    }
    g += X[i] * 9 + Y[i];
    group[g].push_back(i);
  }
  int mx_g = 0;
  for (int i = 1; i < 90; i++){
    if (group[i].size() > group[mx_g].size()){
      mx_g = i;
    }
  }
  int K = group[mx_g].size();
  cout << K << endl;
  for (int i = 0; i < K; i++){
    cout << group[mx_g][i] + 1;
    if (i < K - 1){
      cout << ' ';
    }
  }
  cout << endl;
}