#include <bits/stdc++.h>
using namespace std;
int a[111111], b[111111];
vector<int> v;
long long t[555][555];
int main() {
  int n;
  cin >> n;
  int r, c;
  for (int i = 0; i < n; i++) {
    for (int j = 0; j < n; j++) {
      cin >> t[i][j];
      if (t[i][j] == 0) {
        r = i;
        c = j;
      }
    }
  }
  if (n == 1) {
    cout << "1" << endl;
    return 0;
  }
  long long sum = 0;
  if (r == 0) {
    for (int i = 0; i < n; i++) sum += t[1][i];
  } else {
    for (int i = 0; i < n; i++) sum += t[0][i];
  }
  long long lel = 0;
  for (int i = 0; i < n; i++) {
    lel += t[r][i];
  }
  if (lel >= sum) {
    cout << "-1";
    return 0;
  }
  t[r][c] = sum - lel;
  for (int i = 0; i < n; i++) {
    long long cur = 0;
    for (int j = 0; j < n; j++) {
      cur += t[i][j];
    }
    if (cur != sum) {
      cout << "-1";
      return 0;
    }
  }
  for (int i = 0; i < n; i++) {
    long long cur = 0;
    for (int j = 0; j < n; j++) {
      cur += t[j][i];
    }
    if (cur != sum) {
      cout << "-1";
      return 0;
    }
  }
  long long cur = 0;
  for (int i = 0; i < n; i++) {
    cur += t[i][i];
  }
  if (cur != sum) {
    cout << "-1";
    return 0;
  }
  cur = 0;
  for (int i = 0; i < n; i++) {
    cur += t[i][n - 1 - i];
  }
  if (cur != sum) {
    cout << "-1";
    return 0;
  }
  cout << t[r][c];
  return 0;
}
