/**
 *  American Computer Science League  Contest #1:  Senior Division
 */
package senior;

import java.io.*; // package contains BufferedReader class
import java.util.*; // package contains StringTokenizer class

class Triangles
{   
   private static double AB = 0, BC = 0, AC = 0, DE = 0, EF = 0, DF = 0;
   
   public static void main( String[] args ) throws IOException
   {
      // Use BufferedReader to capture data from data file on disk drive
      BufferedReader in = new BufferedReader(
                              new FileReader( "TestSr.in" ) );
      
      for( int i = 0; i < 5; i++ )
      {
         StringTokenizer st = new StringTokenizer( in.readLine() );
         
         AB = Double.parseDouble( st.nextToken() );
         BC = Double.parseDouble( st.nextToken() );
         AC = Double.parseDouble( st.nextToken() );
         DE = Double.parseDouble( st.nextToken() );
         EF = Double.parseDouble( st.nextToken() );
         DF = Double.parseDouble( st.nextToken() );

         if( legal(AB, BC, AC) && legal(DE, EF, DF) )
            findProportionality();
         else
            System.out.println( "NOT VALID" );
         
      } // end for

      System.exit( 0 ); // don't omit this

   } // end main()
   
   private static boolean legal(double x, double y, double z)
   {
      double max = Math.max( Math.max( x,y ) , z ) ;
 
      if (max == x) if ( max < y + z ) return true ;  // assumes max == x
      if (max == y) if ( max < x + z ) return true ;  // assumes max == y 
      if (max == z) if ( max < x + y ) return true ;  // assumes max == z   
      return false ;
   } // end legal()
   
   private static void findProportionality()
   {
           
       if      ( AB/DE == BC/EF && AB/DE == AC/DF) System.out.println("DEF");
       else if ( AB/DE == BC/DF && AB/DE == AC/EF) System.out.println("EDF");
      
       else if ( AB/EF == BC/DE && AB/EF == AC/DF) System.out.println("FED");
       else if ( AB/EF == BC/DF && AB/EF == AC/DE) System.out.println("EFD");
       
       else if ( AB/DF == BC/DE && AB/DF == AC/EF) System.out.println("FDE");
       else if ( AB/DF == BC/EF && AB/DF == AC/DE) System.out.println("DFE");
       
       else System.out.println("NONE");      
   }
   
} // // end class Triangles [ Senior Division ]