Const
 Eps=0.0001;
 Xbeg=0.1;
 Xfin=0.8;
 DX=0.05;
VAR
 N,i,k:Word;
 S,X,a:Real;

BEGIN
 N:=Round((Xfin-Xbeg)/DX);
 WriteLn('   X        Result      Number of items     Accurate value');
 For i:=0 to N do
  begin
   X:=Xbeg+DX*i;
   S:=0;
   k:=0;
   Repeat
    Inc(k);
    a:=Cos(X*2*k)/(4*k*k-1);
    S:=S+a;
   Until Abs(a)<Eps;
   WriteLn(X:6:3,S:12:6,k:12,0.5-Pi/4*Abs(Sin(X)):24:6);
  end;
 Readln;
END.