word decimal
word decimal
word decimal

##</code><code>##

open F1,"F1.dat" or die "Can't open F1.dat: $!\n";
open F2,"F2.dat" or die "Can't open F2.dat: $!\n";

   my (%hash1,%hash2);
   while (<F1>)
   {
      /(\w*) (\d*)/ ;
      $hash1{$1} = $2 ;
   }
   close F1;

   while (<F2>)
   {
      /(\w*) (\d*)/ ;
      $hash2{$1} = $2 ;
   }
   close F2;
   
   open MERGED,">merge.dat" or die "Can't open merge.dat:$!\n";
   foreach (sort keys %hash2)
   {
      if (defined($hash1{$_}))
      {
         print MERGED "$_ $hash1{$_}\n" ;
      } else {
         print MERGED "$_ $hash2{$_}\n" ;
      }
    }
    close MERGED;

##</code><code>##

word decimal word....