№5

#include <bits/stdc++.h>
#include <stdio.h>
#define REP(var, start, end) for(int var = start; var < end; var++)
using namespace std;

int main()
{
  int n;
  bool isSymmetrical = true;

  scanf("%d", &n);
  int array[n][n];

  //fill
  REP(x, 0, n)
  {
    REP(y, 0, n)
    {
      scanf("%d ", &array[x][y]);
    }
  }

REP(x, 0, n)
  {
    REP(y, 0, n)
    {
        if (x-y == 0 ) continue;

        if(array[x][y] != array[y][x])
        {
            printf("NO");
            return 0;
        }
    }

  }

  printf("YES");


  return 0;
}