use strict;
use warnings;

my ($x, $y, $z, $w) = (1, 2, 3, 4);

my @A = sort { $a <=> $b } $x, $y, $z, $w;

my $ok = 1;
while (@A) {
  $ok = 0 if @A >= 2 && $A[0] == $A[1];
  shift @A;
}
print $ok;