#!/usr/bin/perl -w

use strict;

my @x; # your x values
my @y; # your y values

open FH, 'your file'; # whatever your data file is

while (my $line = <FH>){
       my @z = split ' ', $line; # split on space to get 
                                 # your values in an array
       push(@x ,unshift @z); # take first element of z and 
                             # add it to x
       push(@y,$_) foreach(@z); # add the rest to y
       }
close FH;