#include <iostream>

using namespace std;

int ap[10001];
int a[1001][1001];

int main()
{ int n,m,j,i;
 long long maxim;
 maxim=0;

    cin>>n>>m;

    for( i = 1; i <= n ; ++i)
         for ( j = 1 ; j <= m ; ++j) {cin>>a[i][j];
                                        if(a[i][j]>maxim) maxim=a[i][j];}

for( j = 1 ; j <= m ; ++ j ) {ap[a[1][j]]++;
                            ap[a[n][j]]++;}

  for( i = 1 ; i <= n ; ++i) {ap[a[i][1]]++;
                            ap[a[i][m]]++;


  }

  for( i =1 ; i <=maxim ; ++i) if(ap[i]>0) cout<<i<<" ";

  return 0;

}