I tried to compile it in Delphi and it works. I tried to compile it in Free Pascal and it works. What is the problem? I used Quick Sort.
    Here is my sorce:
    I hope you will find the problem.
   type vec=array[1..150000] of longint;
var i,n,k:longint;
    a:vec;
    b:vec;

procedure poz(li,ls:longint);
var i,j,c,i1,j1,as:longint;
begin
     i1:=0;
     j1:=-1;
     i:=li;
     j:=ls;
     while i<j do
          begin
               if a[i]<a[j] then
                 begin
                      c:=a[j];
                      a[j]:=a[i];
                      a[i]:=c;
                      as:=b[j];
                      b[j]:=b[i];
                      b[i]:=as;
                      c:=i1;
                      i1:=-j1;
                      j1:=-c;
                  end;
               i:=i+i1;
               j:=j+j1;
           end;
     k:=i;
end;

procedure quick(li,ls:longint);
begin
     if li<ls then
       begin
            poz(li,ls);
            quick(li,k-1);
            quick(k+1,ls);
        end;
end;

begin
     readln(n);
     for i:=1 to n do readln(b[i],a[i]);
     quick(1,n);
     for i:=1 to n do writeln(b[i],' ',a[i]);
end.