use strict;
use warnings;
use 5.12.4;

chomp(my $n = <STDIN>);
chomp(my @line = <STDIN>);

my $result = 0;

for my $now_point (@line){
    for my $target_point (@line){

        my @now_point = split / /, $now_point;
        my @target_point = split / /, $target_point;

        my $x = abs ($now_point[0] - $target_point[0]);
        my $y = abs ($now_point[1] - $target_point[1]);
        my $route = sqrt ($x*$x + $y*$y);

        if( $result < $route ){
            $result = $route;
        }
    }
}

print $result,"\n";