#include <bits/stdc++.h> using namespace std; #ifdef _RUTHEN #include <debug.hpp> #else #define show(...) true #endif using ll = long long; #define rep(i, n) for (int i = 0; i < (n); i++) template <class T> using V = vector<T>; int main() { ios::sync_with_stdio(false); cin.tie(0); int N, M; cin >> N >> M; V<V<ll>> D(N, V<ll>(M)); rep(i, N) { rep(j, M) cin >> D[i][j]; sort(D[i].begin(), D[i].end()); } const ll INF = 1LL << 60; V<ll> dp(M, 0); rep(i, N - 1) { V<V<pair<int, ll>>> G(M + 1); rep(j, M) { int lb = lower_bound(D[i + 1].begin(), D[i + 1].end(), D[i][j]) - D[i + 1].begin(); G[lb].push_back({1, dp[j]}); int ub = lower_bound(D[i + 1].begin(), D[i + 1].end(), D[i][j] + dp[j]) - D[i + 1].begin(); G[ub].push_back({2, dp[j]}); G[ub].push_back({3, -D[i][j]}); } show(G); V<ll> np(M, INF); multiset<ll> S1, S2; S1.insert(INF); S2.insert(INF); rep(j, M) { for (auto [t, v] : G[j]) { if (t == 1) { S1.insert(v); } else if (t == 2) { S1.extract(v); } else { S2.insert(v); } } np[j] = min({*S1.begin(), D[i + 1][j] + *S2.begin(), INF}); show(S1, S2); } swap(dp, np); show(dp); } ll ans = *min_element(dp.begin(), dp.end()); if (ans >= INF) ans = -1; cout << ans << '\n'; return 0; }