uses crt;
var s,e,t:real;
n:integer;
begin
clrscr;
write('e=');readln(e);
if e>=2 then s:=2
else
begin
s:=2;
t:=2;
n:=1;
while abs(t)>=e do
begin
n:=n+1;
t:=t*2/(n-1);
s:=s+t;
end;
end;
write('S=',s:0:5);
readln
end.
uses crt;
var s,e,t:real;
n:integer;
begin
clrscr;
write('e=');readln(e);
if e>=2 then s:=2
else
begin
s:=2;
t:=2;
n:=1;
while abs(t)>=e do
begin
n:=n+1;
t:=t*2/(n-1);
s:=s+t;
end;
end;
write('S=',s:0:5);
readln
end.