#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 each(e, v) for(auto &e: v)
#define pb push_back
#define eb emplace_back
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define sz(x) (int)x.size()
using ll = long long;
using pii = pair<int, int>;
using pil = pair<int, ll>;
using pli = pair<ll, int>;
using pll = pair<ll, ll>;
const int MOD = 1000000007;
//const int MOD = 998244353;
const int inf = (1<<30)-1;
const ll INF = (1LL<<60)-1;
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;};

struct io_setup{
    io_setup(){
        ios_base::sync_with_stdio(false);
        cin.tie(NULL);
        cout << fixed << setprecision(15);
    }
} io_setup;

template<bool directed = false>
struct Graph{
    struct edge{
        int to, id;
        edge(int to, int id) : to(to), id(id) {}
    };

    vector<vector<edge>> es;
    const int n;
    int m;

    Graph(int n) : es(n), n(n), m(0) {}

    void add_edge(int from, int to){
        es[from].emplace_back(to, m);
        if(!directed) es[to].emplace_back(from, m);
        m++;
    }

    bool solve(int i){
        vector<edge> ids;
        each(e, es[i]){
            if(sz(es[e.to]) >= 2) ids.eb(e);
        }

        if(sz(ids) >= 2){
            vector<int> ans(4);
            auto e1 = ids[0], e2 = ids[1];
            ans[1] = e1.id, ans[2] = e2.id;
            each(e, es[e1.to]){
                if(e.to != i){
                    ans[0] = e.id;
                    break;
                }
            }
            each(e, es[e2.to]){
                if(e.to != i){
                    ans[3] = e.id;
                    break;
                }
            }

            rep(i, 4) cout << ans[i]+1 << (i == 3? '\n' : ' ');
            return true;
        }

        return false;
    }
};

int main(){
    int H, W, N; cin >> H >> W >> N;

    Graph G(H+W);

    rep(i, N){
        int x, y; cin >> x >> y; x--, y--;
        G.add_edge(x, H+y);
    }

    rep(i, H){
        if(G.solve(i)) return 0;
    }

    cout << "-1\n";
}