uses
  SysUtils;

const
 x0=0;
 xk=2*3.14;
 eps=1E-7;

var
 n,i:integer;
 s,x,h,s1,x1,delta:real;

function f(y:real):real;
begin
 f:=cos(x);
end;

function Antider(y:real):real;
 begin
  Antider:=-y*y*y+y*y*15/2-y*18;
 end;

Begin
 n:=2;
 s:=(f(x0)+f((x0+xk)/2))*(xk-x0)/4+(f((x0+xk)/2)+f(xk))*(xk-x0)/4;
 delta:=1;
 While delta>eps do
  begin
   s1:=s;
   n:=n+2;
   h:=(xk-x0)/n;
   x:=x0;
   s:=0;
   for i:=1 to n do
    begin
     x1:=x+h;
     s:=f(x)+f(x1)+s;
     x:=x1;
    end;
   s:=s*h/2;
   delta:=abs(s-s1);
  end;
 writeln('Trapezium:');
 writeln('s = ',s:0:10);
 writeln('s1= ',s1:0:10);
 writeln('n= ',n);
 writeln;

 n:=2;
 s:=(f(x0)+f((x0+xk)/2)*4+f(xk))*(xk-x0)/6;
 delta:=1;
 While delta>eps do
  begin
   s1:=s;
   n:=n+2;
   h:=(xk-x0)/n;
   x:=x0;
   s:=0;
   for i:=1 to (n div 2) do
    begin
     x1:=x+h*2;
     s:=f(x)+f(x+h)*4+f(x1)+s;
     x:=x1;
    end;
   s:=s*h/3;
   delta:=abs(s-s1);
  end;
 writeln('Simpson:');
 writeln('s = ',s:0:10);
 writeln('s1= ',s1:0:10);
 writeln('n= ',n);
 writeln;
 Write('Accurate value: ');
 Writeln((Antider(xk)-Antider(x0)):0:10);
 Readln
End.

function Antider(y:real):Real;
 begin
  Antider:=sin(y);
 end;