import java.io.BufferedReader import java.io.InputStream import java.io.InputStreamReader import java.lang.AssertionError import java.util.* import kotlin.math.abs import kotlin.math.max import kotlin.math.min val MOD = 1_000_000_007 data class Point(val i: Int, val h: Int, val w: Int) class Solver(stream: InputStream, private val out: java.io.PrintWriter) { private val reader = BufferedReader(InputStreamReader(stream), 32768) fun solve() { val (Hmax, Wmax, N) = na(3) val P = Array(N){Point(it, ni()-1, ni()-1)} val H = Array(Hmax){ mutableListOf()} val W = Array(Wmax){ mutableListOf()} for (i in P) { H[i.h].add(i.i) W[i.w].add(i.i) } fun find(h: Int, w: Int, notH: Boolean): Int { for (i in W[w]) { if (notH && P[i].h != h) return i if (!notH && P[i].h == h) return i } return -1 } for (h in 0 until Hmax) { val ws = mutableListOf() for (i in H[h].indices) { val j = H[h][i] val w = P[j].w if (W[w].size >= 2) { ws += w } } if (ws.size >= 2) { val (w1, w2) = ws.take(2) val p1 = find(h, w1, true) val p2 = find(h, w1, false) val p3 = find(h, w2, false) val p4 = find(h, w2, true) out.println(4) out.println(intArrayOf(p1, p2, p3, p4).map{it+1}.joinToString(" ")) return } } out.println(-1) } private val isDebug = try { // なんか本番でエラーでる System.getenv("MY_DEBUG") != null } catch (t: Throwable) { false } private var tokenizer: StringTokenizer? = null private fun next(): String { while (tokenizer == null || !tokenizer!!.hasMoreTokens()) { tokenizer = StringTokenizer(reader.readLine()) } return tokenizer!!.nextToken() } private fun ni() = next().toInt() private fun nl() = next().toLong() private fun ns() = next() private fun na(n: Int, offset: Int = 0): IntArray { return IntArray(n) { ni() + offset } } private fun nal(n: Int, offset: Int = 0): LongArray { val res = LongArray(n) for (i in 0 until n) { res[i] = nl() + offset } return res } private fun na2(n: Int, offset: Int = 0): Array { val a = Array(2){IntArray(n)} for (i in 0 until n) { for (e in a) { e[i] = ni() + offset } } return a } private inline fun debug(msg: () -> String) { if (isDebug) System.err.println(msg()) } /** * コーナーケースでエラー出たりするので、debug(dp[1])のように添え字付きの場合はdebug{}をつかうこと */ private inline fun debug(a: LongArray) { debug { a.joinToString(" ") } } private inline fun debug(a: IntArray) { debug { a.joinToString(" ") } } private inline fun debug(a: BooleanArray) { debug { toString(a) } } private inline fun toString(a: BooleanArray) = run{a.map { if (it) 1 else 0 }.joinToString("")} private inline fun debugDim(A: Array) { if (isDebug) { for (a in A) { debug(a) } } } private inline fun debugDim(A: Array) { if (isDebug) { for (a in A) { debug(a) } } } private inline fun debugDim(A: Array) { if (isDebug) { for (a in A) { debug(a) } } } /** * 勝手にimport消されるのを防ぎたい */ private fun hoge() { min(1, 2) max(1, 2) abs(-10) } private inline fun assert(b: Boolean) = run{if (!b) throw AssertionError()} private inline fun assert(b: Boolean, f: () -> String) = run{if (!b) throw AssertionError(f())} companion object { // TestRunnerから呼びたいので単純なmainじゃだめ fun main() { val out = java.io.PrintWriter(System.out) Solver(System.`in`, out).solve() out.flush() } } } /** * judgeから呼ばれる */ fun main() = Solver.main()