program points;

{$APPTYPE CONSOLE}

uses
  SysUtils;

var xy:array[1..1000000,1..2] of integer;
s:int64;
i,n,j:integer;
begin
assign(input,'points.dat');
reset(input);
assign(output,'points.sol');
rewrite(output);
readln(n);
for i:=1 to n do readln(xy[i,1],xy[i,2]);
s:=0;
for i:=1 to n do
for j:=i+1 to n do
s:=s+sqr(xy[i,1]-xy[j,1])+sqr(xy[i,2]-xy[j,2]);
writeln(s);
close(input);
close(output);
end.