program pal9;
uses crt;
var
n: integer;
x, e, a, s: real;
begin
repeat
write('0<=x<=2 x=');
readln(x);
until (x >= 0) and (x <= 2);
write('e=');
readln(e);
if e >= abs(x - 1) then
s := s - 1
else
begin
s := 0;
a := 1;
n := 1;
repeat
a := a * (x - 1) / n;
s := s + a;
n := n + 1;
until abs(a) < e;
end;
writeln('s=', s:0:10);
readln;
end.