my @substr_mat = ();
	my $substr_tmp1 = ();
	my $substr_tmp2 = ();
	my $start = ();
	my $end = ();	
	my %map1 = ();
	my %map2 = ();
	my $m = 0;
	
	foreach my $str (sort {($substrings{$b}[1]-$substrings{$b}[0]) <=> ($substrings{$a}[1]-$substrings{$a}[0]) || $substrings{$a}[0] <=> $substrings{$b}[0]} keys %substrings){			
		$substr_tmp1 = '';
		$substr_tmp2 = '';
		
		$start = -1; $end = -1;
		for( my $i = $substrings{$str}[0]; $i <= $substrings{$str}[1]; $i++){
			if( ! exists $map1{$i}){
       			$map1{$i} = 1;
				$substr_tmp1 .= "$s1[$i] ";
				if($start == -1){
					$start = $end = $i;
				} else {
					$end = $i;
				}
			}
       	}
		next if $start == -1;
		
		$start = -1; $end = -1;
		for( my $i = $substrings{$str}[2]; $i <= $substrings{$str}[3]; $i++){
			if( ! exists $map2{$i}){
       			$map2{$i} = 1;
				$substr_tmp2 .= "$s2[$i] ";
				if($start == -1){
					$start = $end = $i;
				} else {
					$end = $i;
				}
			}
       	}
		next if $start == -1;
		
		if( length($substr_tmp1) <= length($substr_tmp2) ){
			$substr_mat[$m++] = $substr_tmp1;
		} else {
				$substr_mat[$m++] = $substr_tmp2;
		}		
	}