{
TASK:green
LANG:PASCAL
}
type b=record
        x:integer;
        y:integer;
       end;
type tarr=array[1..100] of b;
var
 a:tarr;
 i,m,l,p,k:integer;
 h,n:real;
function find(c,d:integer):real;
 var
  l:real;
 begin
  l:={sqrt(}sqr(a[c].x-a[d].x)+sqr(a[c].y-a[d].y){)};
  find:=sqrt(l);
 end;
function lic(a,b,c:real):real;
 var
  x:real;
 begin
  x:=sqr((a*a+c*c-b*b)/2*c);
  lic:=c*sqrt(x+b*b)/2;
 end;
function test(m:integer;h:real):real;
 var
  x,y,z,n:real;
  i:integer;
 begin
  n:=999999999;
  x:=find(1,2);
  for i:=2 to m-1 do begin
                      if i=2 then n:=0;
                      y:=find(i,i+1);
                      z:=find(i+1,1);
                      n:=n+lic(x,y,z);
                      x:=z;
                      if n>h then break;
                     end;
  test:=n;
 end;
begin
 l:=1;
 n:=999999999;
 repeat
  read(m);
  for i:=1 to m do read(a[i].x,a[i].y);
  readln;
  h:=test(m,n);
  if h<n then begin
               n:=h;
               p:=l;
               k:=m;
              end;
  if (h=n)and(m<k) then begin
                         n:=h;
                         p:=l;
                         k:=m;
                        end;

  l:=l+1;
 until m=0;
 writeln(p);
 {writeln(lic(5,6,7):0:5);}
end.