program tinhtong;

uses crt;

var i,j,n,t : integer; s: real;

begin

s:=0;

write('nhap vao so n'); readln(n);

for i:=1 to n do

begin

t:=1;

for j:= 1 to i do t:= t*j;

s:= s+ 1/t;

end;

write(' tong S = ',s:7:2);

readln;

end.