use strict;
use warnings;

open(FH1,"file1.txt");
open(FH2,"file2.txt");
my @array=<FH2>;
chomp @array;

while(my $var=<FH1>){
  chomp $var;
  my ($first,$second)=split(/\s+/,$var);
  my @grepped= grep {/\Q$second\E/} @array;
  print "$first\t$grepped[0]\n";
}