program iteratcia;
uses crt;
var x,eps,xn,an,s,f,t:real;
    kk,i,n:integer;
    ind:boolean;
begin
  clrscr;
  repeat
  ind:=true;
  writeln('riad E(n=1..+00)(x^2n/(2n)!) pry X e [-10:10]');
  writeln('vvedit x');  readln(x);
  if (x<-10) or (x>10) then
    begin writeln ('nevirne x');
    ind:=false;
    end;
  until ind;
  writeln('Vvedit eps'); readln(eps);
  writeln('Vvedit limit kilkosti iteratsii'); readln(kk);
  xn:=x;
  n:=0;
  s:=0;
  repeat
   inc(n);
   xn:=xn*xn;
   f:=1;
  for i:=1 to (2*n) do
    an:=xn/f*i; s:=s+an;
  until (abs(an)<eps) or (n>=kk);
  if (n>kk) then writeln('Perevyscheno limit kilkosti krokiv');
  writeln('rezultat:');
  writeln('Kilkist krokiv iteratsii:',n);
  writeln('Nablyzhene znachennia funktsii:',s:1:12);
  t:=(exp(x)+exp(-x))/2-1;
  writeln('Tochne znachennia funktsii:',t:1:12);
  writeln(' |t-s|=', abs(t-s):1:12);
 readln;
end.