求大神帮忙

var x1,x2,y1,y2,n,i,sa,sb,aa,ba,ans:longint;
    a:array[0..100000,1..2]of longint;
begin
  readln(x1,y1,x2,y2);
  readln(n);
  for i:=1 to n do
    readln(a[i,1],a[i,2]);
  aa:=0;
  ba:=0;
  for i:=1 to n do
    begin
      sa:=sqr(x1-a[i,1])+sqr(y1-a[i,2]);
      sb:=sqr(x2-a[i,1])+sqr(y2-a[i,2]);
      if (sa>aa)and(sb>ba)
        then
          begin
            if sa-aa<sb-ba then aa:=sa;
            if sa-aa>sb-ba then ba:=sb;
            if sa-aa=sb-ba then aa:=sa;
          end;
    end;
  ans:=aa+ba;
  writeln(ans);
end.