Var
 R:real;
 i:Byte;

Function Tg(x:real):real;
begin
 tg:=Sin(x)/Cos(x);
end;

Begin
 R:=Tg(1);
 For i:=1 to 8 do
  R:=Tg((2*i+1)+R);
 Writeln('R= ',R:0:5);
 Readln;
End.