use strict;
use Getopt::Std;
my $USAGE="USAGE: sample.pl -f <infile1> -i <infile2> -o <outfile>";
my %Options;
getopts('f:i:o:', \%aOptions);
my $infile1= $aOptions{f} || die "** $USAGE.\nERROR missing input file1 ** ";
my $infile2= $aOptions{i} || die "** $USAGE.\nERROR missing input file2 ** ";
my $outfile= $aOptions{o} || die "** $USAGE.\nERROR missing output file ** ";