chomp(my $params_num = <STDIN>);
chomp(my $params_line = <STDIN>);
my @params = split(/\s/, $params_line);
@params = keys %{{ map {$_ => 1} @params }};
@params = sort {$a <=> $b} @params;

my $times = scalar(@params)-1;
my $short;
for (my $i = 0; $i < $times; $i++) {
    my $len = $params[$i + 1] - $params[$i];
    $short = ($short > $len || !defined($short)) ? $len : $short;
}

print ((defined($short) ? $short : 0) . "\n");