FUNCTION e(x:real):real;
VAR s,sn,a,z:real; i,m:integer;
BEGIN
  m:=0; z:=x;
  WHILE abs(z)>1 DO
  BEGIN m:=m+1; z:=z/2 END;
  sn:=1; a:=1; i:=0;
  REPEAT
    i:=i+1; s:=sn; a:=a*z/i;
    sn:=s+a
  UNTIL sn=s;
  FOR i:= 1 TO m DO sn:=sqr(sn);
  e:=sn
END;