#include <stdio.h>
#include <assert.h>

#define TRUE 1
#define FALSE 0
#define MAX 100

int main()
{
  double M[MAX][MAX];
  int n, i, j;
  int acheinaonulo; /*encontrou elemento naonulo acima da diagonal*/

  scanf("%d", &n);
  assert( n <= MAX );

  for (i = 0; i < n; i++)
    for (j = 0; j < n; j++)
      scanf("%lf", &M[i][j]);

  acheinaonulo = FALSE;
  for ( i = 0; i < n; i++ )
    for ( j = i + 1; j < n; j++ )
      if ( M[i][j] != 0 )
	acheinaonulo = TRUE;

  if (acheinaonulo == FALSE)
    printf("A matriz eh triangular inferior.\n");
  else printf("A matriz NAO eh triangular inferior.\n");

  return 0;
}