#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for(int i = 0; i < n; i++)
#define rep2(i, x, n) for(int i = x; i <= n; i++)
#define rep3(i, x, n) for(int i = x; i >= n; i--)
#define elif else if
#define sp(x) fixed << setprecision(x)
#define pb push_back
#define eb emplace_back
#define all(x) x.begin(), x.end()
#define sz(x) (int)x.size()
using ll = long long;
using ld = long double;
using pii = pair<int, int>;
using pil = pair<int, ll>;
using pli = pair<ll, int>;
using pll = pair<ll, ll>;
const ll MOD = 1e9+7;
//const ll MOD = 998244353;
const int inf = (1<<30)-1;
const ll INF = (1LL<<60)-1;
const ld EPS = 1e-10;
template<typename T> bool chmax(T &x, const T &y) {return (x < y)? (x = y, true) : false;};
template<typename T> bool chmin(T &x, const T &y) {return (x > y)? (x = y, true) : false;};

int main(){
    int N;
    cin >> N;
    vector<int> cnt[10][9];
    rep(i, N){
        int X, Y;
        cin >> X >> Y;
        int x = X%10, y = Y%9;
        if(Y%18 >= 9) x += 5, x %= 10;
        cnt[x][y].pb(i);
    }
    int M = 0;
    pii p = pii(-1, -1);
    rep(i, 10){
        rep(j, 9){
            if(chmax(M, sz(cnt[i][j]))) p = pii(i, j);
        }
    }
    cout << M << endl;
    for(auto &e: cnt[p.first][p.second]) cout << e+1 << ' '; cout << endl;
}