program obolonka;

var x,y:array[1..100] of real;
r,v:array[1..100] of integer;
xmin:real;
start,finish,lich,n,i,j,k:integer;
f:text;
poisk:boolean;
begin
{??????? ????????? ?????? ????????????}
assign(f,'input.txt');
reset(f);
readln(f,n);
for i:=1 to n do
readln(f,x[i],y[i]);
close(f);
{????? ???????? ????? ?????}
xmin:=x[1];
for i:=2 to n do
if x[i]<xmin then begin xmin:=x[i]; start:=i;end;
v[start]:=1;
r[1]:=start;
k:=1;

{????? ????????? ?????}
poisk:=true;
while poisk do
begin
poisk:=false;
for i:=1 to n do
              if (v[i]=0) then begin
                              k:=k+1;
                              finish:=i;
                              v[finish]:=k;
                              r[k]:=finish;
                              lich:=0;
              for j:=1 to n do
                if (x[finish]-x[start])*(y[j]-y[finish])-(x[j]-x[finish])*(y[finish]-y[start])<0 then
                lich:=lich+1;
{writeln(x[start]:2:0,'  ',y[start]:2:0);
writeln(x[finish]:2:0,'  ',y[finish]:2:0);
writeln(lich);
readln;}
if lich=0 then begin start:=finish;poisk:=true;end else begin v[finish]:=0;k:=k-1;end
end;
   end;
{????????? ??????????}
assign(f,'output.txt');
rewrite(f);
for i:=1 to k do
writeln(f,x[r[i]]:2:2,' ',y[r[i]]:2:2);
close(f);
end.