program p1;  uses crt;
  var i,j,n,sol:integer;
      a:array[1..100] of integer;
begin  clrscr;
  write('n=');readln(n);
  for i:=2 to n do
    a[i]:=i-1;
  for i:=2 to n do begin
     sol:=sol+a[i];

                   end;
  sol:=sol*2;
  sol:=sol+1;
  writeln('solutia=',sol);
  readln;
end.