program btsydn;
uses crt;
var n, i, j, u: integer;
s: real;
begin
clrscr;
write('Nhap n = '); readln(n);
if n>50 then write('n<=50, nhap sai hay nhap lai!') else
s:=0
begin
for i:=2 to n+1 do
begin
u:=1;
for j:=1 to i-1 do u:=u*j;
s:=s+i/u;
end;
write('S = ', s);
end;
readln
end.