#pragma GCC optimize("Ofast,unroll-loops,fast-math,inline-functions,reorder-functions,omit-frame-pointer,tree-vectorize")
#include "bits/stdc++.h"
using namespace std;
#define rep(i,a,b) for(int i=(a); i<(b); ++i)
#define all(x) x.begin(),x.end()
#define sz(x) int(x.size())
typedef vector<int> vi;
typedef vector<vi> vvi;

#include <ext/pb_ds/assoc_container.hpp>
using namespace __gnu_pbds;

const int N = 5e4;
gp_hash_table<int, int> mp[N*3];

int main(){
    cin.tie(NULL),ios::sync_with_stdio(false);
    
    int n; cin >> n;
    vi coords1,coords2;
    coords1.reserve(N*2+10);
    coords2.reserve(N*2+10);

    vvi lists(n);
    for(auto& v : lists){
        int k; cin >> k;
        v.resize(k);
        for(auto& x : v) {
            cin >> x;
            coords1.push_back(x);
        }
    }
    sort(all(coords1));
    coords1.erase(unique(all(coords1)),end(coords1));
    for(auto& v : lists) for(auto& x : v) 
        x = lower_bound(all(coords1),x)-begin(coords1);
    /*
    preprocessing to remove super small nodes
    */
    {
        vi cnt(sz(coords1));
        for(auto& v : lists) for(auto& x : v) cnt[x]++;
        for(auto& v : lists){
            vi nxt;
            nxt.reserve(sz(v));
            for(auto x : v) if (cnt[x] >= 2) {
                nxt.push_back(x);
                coords2.push_back(x);
            }
            v = nxt;
        }
        sort(all(coords2));
        coords2.erase(unique(all(coords2)),end(coords2));
        for(auto& v : lists) for(auto& x : v)
            x = lower_bound(all(coords2),x)-begin(coords2);
    }

    /*
    build graph
    */
   
    int m = sz(coords2);
    const int B = cbrt((n+m)/2);
    vvi adj(n + m), large(n+m), supl(n+m);
    rep(i,0,n){
        for(auto to : lists[i]) {
            adj[n+to].push_back(i);
            adj[i].push_back(n+to);
        }
    }rep(i,0,n+m) if (sz(adj[i]) >= B)
        for(auto j : adj[i]) if (sz(adj[j]) >= B)
            large[i].push_back(j);

    // run algo
    auto print = [&](array<int,4> ans) -> void {
        sort(all(ans));
        cout << coords1[coords2[ans[2]-n]] << ' '; 
        cout << coords1[coords2[ans[3]-n]] << ' ';
        cout << ans[0]+1 << ' ' << ans[1]+1 << '\n';
        exit(0); 
    };
    
    auto add = [&](int u, int v, int mid) -> void {
        auto& cur = mp[u][v];
        if (cur > 0 and cur != mid+1){
            // we found sol!
            array<int,4> ans = {u,v,mid,cur-1};
            print(ans);
        }
        cur = mid+1;
    };

    rep(i,0,n+m) {
        sort(all(adj[i]));
        const int ss = sz(adj[i]); 
        if (ss < B) {
            // small cent
            rep(u,0,ss) rep(v,u+1,ss)
                add(adj[i][u],adj[i][v],i);
        }else{
            // large trip 
            int st = sz(large[i]);
            rep(u,0,st) rep(v,u+1,st)
                add(large[i][u],large[i][v],i);
        }
    }
    // SLL ears
    rep(i,0,n+m) if (sz(adj[i]) < B)
        for(auto mid : adj[i]) if (sz(adj[mid]) >= B)
            for(auto j : large[mid]) add(min(i,j),max(i,j),mid);

    cout << "impossible\n";
}