#include <stdio.h>
#include <stdlib.h>

#define N 1050

#define setbit1(x,y) ( a[x][y >> 3] |=  (1 << (y & 7)) )
#define setbit0(x,y) ( a[x][y >> 3] &= ~(1 << (y & 7)) )
#define getbit(x,y)  ( a[x][y >> 3] &   (1 << (y & 7)) )

int n, s, x, lev;
int a[N][N/8], d[32010];

void read ()
{
   int i, j, v, x = 0;

   //freopen( "1176.in", "rt", stdin );
   scanf( "%d%d", &n, &s );
   for ( i = 1; i <= n; i++ )
       for ( j = 1; j <= n; j++ )
       {
          scanf( "%d", &v );
          if ( !v && i != j )
             setbit1( i, j ), x++;
       }
   if ( !x ) exit( 0 );
}

void ciclu (int s)
{
   int j;

   lev++;

   for ( j = 1; j <= n; j++ )
       if ( getbit( s, j ) )
       {
          setbit0( s, j );
          ciclu( j );
       }

   d[++d[0]] = s;
/*   if ( !x || lev == 1 )
      printf( "%d ", s );
   else
      printf( "%d\n%d ", s, s );
   x = s;

   lev--;*/
}

int main ()
{
   int i;

   read();

   ciclu( s );
   for ( i = 1; i < d[0]; i++ )
       printf( "%d %d\n", d[i], d[i + 1] );

   return 0;
}