Program shopkienthuc;
Uses crt;
 Var j,n:integer;
        gt:longint;
        S:real;
Begin
Clrscr;
Write('nhap n='); readln(n);
  If (n<0) then write(#7,'khong thuc hien duoc vi', n,'<0')
Else
  begin
    gt:=1;
    S:=1;
   For j:=1 to n do
Begin
gt:=gt*j;
S:=S+1/gt;
End;
writeln('S=',S:6:2);
Readln;
End;
Readln
End.