var i:integer;n:real;
    begin
        readln(n);i:=0;
        if n>1 then begin writeln('no');end;
        if cos(i*i*i)*sin((100-i)/100)<n then begin
        repeat
        i:=i+1;
        until (cos(i*i*i)*sin((100-i)/100)>n);end;
        writeln(cos(i*i*i)*sin((100-i)/100):4:5);
        end.