// I expect this to be WA
// approach:
// randomly devide 2*n persons in two groups of n persons each
// find optimal pairing between those groups
// @EXPECTED_RESULTS@: WRONG_ANSWER,TIME_LIMIT_EXCEEDED

#include <bits/stdc++.h>
using namespace std;

#define all(x) begin(x), end(x)
#define sz(x) (ll)(x).size()

using ll = long long;
using ld = long double;

constexpr ll LIM = 4001;
constexpr ll INF = 0x3FFF'FFFF'FFFF;

ll costs[LIM][LIM];

// Es muss l<=r sein! (sonst Endlosschleife)
ll match(int l, int r) {
	vector<ll> lx(l), ly(r);
	//xy is matching from l->r, yx from r->l, or -1
	vector<int> xy(l, -1), yx(r, -1), augmenting(r);
	vector<bool> s(l);
	vector<pair<ll, int>> slack(r);

	for (int x = 0; x < l; x++)
		lx[x] = *max_element(costs[x], costs[x] + r);
	for (int root = 0; root < l; root++) {
		augmenting.assign(r, -1);
		s.assign(l, false);
		s[root] = true;
		for (int y = 0; y < r; y++) {
			slack[y] = {lx[root] + ly[y] - costs[root][y], root};
		}
		int y = -1;
		while (true) {
			ll delta = INF;
			int x = -1;
			for (int yy = 0; yy < r; yy++) {
				if (augmenting[yy] < 0) {
					if (slack[yy].first < delta) {
						delta = slack[yy].first;
						x = slack[yy].second;
						y = yy;
			}}}
			if (delta > 0) {
				for (int x = 0; x < l; x++) if (s[x]) lx[x] -= delta;
				for (int y = 0; y < r; y++) {
					if (augmenting[y] >= 0) ly[y] += delta;
					else slack[y].first -= delta;
			}}
			augmenting[y] = x;
			x = yx[y];
			if (x == -1) break;
			s[x] = true;
			for (int y = 0; y < r; y++) {
				if (augmenting[y] < 0) {
					ll alt = lx[x] + ly[y] - costs[x][y];
					if (slack[y].first > alt) {
						slack[y] = {alt, x};
		}}}}
		while (y >= 0) {
			// Jede Iteration vergrößert Matching um 1
			// (können 0-Kanten sein!)
			int x = augmenting[y];
			int prec = xy[x];
			yx[y] = x;
			xy[x] = y;
			y = prec;
	}}
	// Wert des Matchings
	return accumulate(all(lx), 0ll) +
	       accumulate(all(ly), 0ll);
}

ll n, r;
vector<vector<ll>> in;
mt19937 rng(1234567890);

bool solve() {
	vector<ll> perm(2*n);
	for (ll i = 0; i < 2*n; i++) perm[i] = i;
	for (ll _ = 0; _ < 5e7; _ += n*n*n) {
		for (ll i = 0; i < n; i++) {
			for (ll j = 0; j < n; j++) {
				costs[i][j] = 0;
				for (ll k = 0; k < r; k++) {
					costs[i][j] += max(in[k][perm[i]], in[k][perm[j+n]]);
				}
			}
		}
		if (2*match(n, n) >= r*n*(3*n+1)) return true;
		shuffle(all(perm), rng);
	}
	return false;
}


int main(int argc, char *argv[]) {
	ios_base::sync_with_stdio(false);
	cin.tie(nullptr);

	cin >> n >> r;
	in.assign(r, vector<ll>(2*n));
	for (auto& v : in) {
		for (auto& x : v) cin >> x;
	}
	if (!solve()) cout << "im";
	cout << "possible" << endl;
}