#include <bits/stdc++.h>
using namespace std;
int main(){
  int H, W;
  cin >> H >> W;
  vector<vector<int>> A(H, vector<int>(W));
  for (int i = 0; i < H; i++){
    for (int j = 0; j < W; j++){
      if (i == 0 || i == H - 1 || j == 0 || j == W - 1){
        cin >> A[i][j];
      }
    }
  }
  bool ok = true;
  for (int i = 0; i < H - 1; i++){
    if (abs(A[i][0] - A[i + 1][0]) > 1){
      ok = false;
    }
    if (abs(A[i][W - 1] - A[i + 1][W - 1]) > 1){
      ok = false;
    }
  }
  for (int i = 0; i < W - 1; i++){
    if (abs(A[0][i] - A[0][i + 1]) > 1){
      ok = false;
    }
    if (abs(A[H - 1][i] - A[H - 1][i + 1]) > 1){
      ok = false;
    }
  }
  if (!ok){
    cout << -1 << endl;
  } else {
    vector<int> row_ng, col_ng;
    for (int i = 1; i < H - 1; i++){
      if (abs(A[i][0] - A[i][W - 1]) > W - 1){
        row_ng.push_back(i);
      }
    }
    for (int i = 1; i < W - 1; i++){
      if (abs(A[0][i] - A[H - 1][i]) > H - 1){
        col_ng.push_back(i);
      }
    }
    if (row_ng.empty() && col_ng.empty()){
      cout << 0 << endl;
    } else {
      assert(false);
    }
  }
}