var f,g:text;
a:array[1..1500]of record
                     x,y:real;
                     end;
k:longint;
n,i,j,l:integer;
x1,x2,x3:real;
begin
assign(f,'triang.in');
reset(f);
readln(f,n);
for i:=1 to n do
    readln(f,a[i].x,a[i].y);
close(f);
for i:=1 to n-2 do
  for j:=i+1 to n-1 do
     begin
     x1:=sqrt(sqr(a[i].x-a[j].x)+sqr(a[i].y-a[j].y));
     for l:=j+1 to n do
          begin
          x2:=sqrt(sqr(a[i].x-a[l].x)+sqr(a[i].y-a[l].y));
          x3:=sqrt(sqr(a[l].x-a[j].x)+sqr(a[l].y-a[j].y));
          if ((x2+x3)>=x1) and((x1+x3)>=x2) and((x2+x1)>=x3) then
                if (abs(x1-x2)<0.0001) and (abs(x1-x3)<0.0001)then
                                          inc(k);
          end;
    end;
assign(g,'triang.out');
rewrite(g);
writeln(g,k);
close(g);
end.