Const
 a=0.15;
 b=0.75;

function F(x1,z1:Real):Real;
begin
 F:=x1*Sqrt(Sqr(x1)+Sqr(z1));
end;

function Antiderivative(x1,z1:Real):Real;
begin
 Antiderivative:=1/3*Sqrt((Sqr(x1)+Sqr(z1))*(Sqr(x1)+Sqr(z1))*(Sqr(x1)+Sqr(z1)));
end;

procedure rect(zt,et:real; var T:real; var Nt:Integer);
var
 i,N:Integer;
 Sum1,Sum2,h:Real;
begin
 N:=5;
 h:=(b-a)/N;
 Sum1:=0;
 for i:=0 to N-1 do
  Sum1:=Sum1+h*F(a+h*i+h/2,zt);
 Sum2:=Sum1;
 repeat
  Sum1:=Sum2;
  N:=N*2;
  h:=(b-a)/N;
  Sum2:=0;
  for i:=0 to N-1 do
   Sum2:=Sum2+h*F(a+h*i+h/2,zt);
 until ABS(Sum2-Sum1)<et;
 Nt:=N;
 T:=Sum2;
end;

var
 j,M:Integer;
 z,R,Eps:real;
begin
 write('z= ');
 readln(z);
 eps:=0.1;
 for j:=1 to 4 do
  begin
   eps:=Eps/10;
   rect(z,Eps,R,M);
   writeln('Eps= ',Eps:8);
   writeln('Number of steps= ',M);
   writeln('Result: ',R:0:9);
   writeln;
  end;
 writeLn('Accurate value:', (Antiderivative(b,z)-Antiderivative(a,z)):0:9);
 ReadLn;
end.