program abc;


{$mode objfpc}{$H+}
uses Classes, SysUtils,math;


const k=2000;
var a,b,h,s1,s2,s:real;
 i,n,ntest:integer;
 y:array[1..k+1] of real;

function f(x:real):real;
begin
 result:=power(cos(3*x+2),6)/sqrt(1+x*x);
end;

begin

 writeln('a = ');
 readln(a);
 writeln('b = ');
 readln(b);
 ntest:=2;
 while ntest>0 do
 begin
  Writeln('Enter nmber of integerals, less 2000');
  writeln('n = ');
  readln(n);
  ntest:=n mod 2;
 end;
 h:=(b-a)/n;
 y[1]:=f(a);
 y[n+1]:=f(b);
 for i:=2 to n do
 begin
  y[i]:=f(a+h*(i-1));
 end;
 s1:=0;
 s2:=0;
 for i:=2 to n do
 begin
  if (i mod 2)=0 then
   s2:=s2+y[i]
  else
   s1:=s1+y[i];
  end;
 s:=(y[1]+y[n+1]+s1*2+s2*4)*h/3;
 writeln('Integral = ',s);
 readln;
end.