program menu;
uses crt, graph;
const m: array [1..5] of string[20]=('O programme','Vvod ishodnih dannih', 'Raschet', 'Grafik', 'Vihod');
var e: char;
    d,f: integer;
    a,b:real;
    s:real;
    r:boolean;
    gd, gm:integer;
{--------------------}
procedure vibor(c:integer);
var i:word;
begin
     clrscr;
     for i:=1 to 5 do
          begin
               if i=c then
                    textcolor (11)
               else
                    textcolor (15);
               gotoxy (30,9+i);
               write (m[i]);
          end;
end;
{--------------------}
procedure o_programme;
begin
end;
{--------------------------}
function p(str:string):boolean;
var i:integer;
begin
  p:=true;
  for i:=1 to length(str) do
  if ((ord(str[i])<45) or (ord(str[i])>57)) or (ord(str[i])=47) then
  begin
	 p:=false;
	 exit;
  end;
end;
{--------------------------}
procedure vvod_predelov(var a, b:real);
var str:string;
    i:integer;
begin
  clrscr;
  textcolor(15);
  writeLn('Vvedite nizhniy predel i nagmite <Enter>:');
  str:='';
  while str =''do
  begin
	 readln(str);
         if p(str) then val(str, a, i)
	 else
	 begin
		str := '';
		writeLn('Predeli mogut bit'' tol''ko ciframi');
	 end;
  end;
  writeLn;
  writeLn('Vvedite verhniy predel i nagmite <Enter>:');
  str:='';
  while str='' do
  begin
	 readln(str);
	 if p(str) then val(str, b, i)
	 else
	 begin
		str:='';
		writeLn('Predeli mogut bit'' tol''ko ciframi');
	 end;
         if b<=a then
         begin
		str:='';
		writeLn('Verhniy predel mozhet bit'' tol''ko bol''she nizhnego');
	 end;
  end;
  writeLn;
  r:=true;
  textcolor(31);
  writeLn('Nazhmite lubuyu klavishu');
  readkey;
 end;
{--------------------------}
procedure raschet (a, b:real;var S:real);
begin
clrscr;
writeln ('Znachenie dannogo integrala ravno:');
  writeln;
  writeln('  b                ');
  writeln(' -- ');
  writeln(' |  (5-2x)dX = (5b-(2(b^2)/2))-(5a-(2(a^2)/2)) = (5b-(b^2))-(5a-(a^2))');
  writeln('--');
  writeln('a           ');
  writeln;
  if r=false then
  begin
	 writeln('Dlya rascheta integrala vvedite ''a'' i ''b''.');
         writeln;
	 writeln('Nazhmite lubuyu klavishu');
  readkey;
  exit;
  end;
S:=((5*b-b*b)-(5*a-a*a));
writeln ('Integral=',s:6:2);
writeln;
textcolor (31);
writeln('Nazhmite lubuyu klavishu');
readkey;
end;

{--------------------------}
Procedure grafik;
Var x, y,xx, yy, Y2, Y1, Y4, Y3, St, y0, z : Real;
         i:integer;
         t:string;

begin
clrscr;
if r=false then
           begin
        	writeLn('Znachenia predelov ne bili vvedeni. Vvedite ''a'' i ''b''.');
		writeLn;
                textcolor(3);
		writeLn('Nagmite lubuyu klavishu');
		readKey;
		exit;
	    end;
InitGraph(gd, gm, '');
     setfillstyle(solidfill,15);
     bar (65,90,575,420);

     setcolor (3);
     for i:=1 to 11 do
         line (65,60+30*i,575,60+30*i);
     for i:=1 to 18 do
         line (35+30*i,90,35+30*i,420);

     y2:=-1000000;
     y1:= 1000000;
     x:=80;
     while (x<=560) do
	begin
	     xx:=(x-80)/505*(b-a)+a;
             yy:=5-2*xx;
	     if (y2<yy) then y2:=yy;
	     if (y1>yy) then y1:=yy;
	     x:=x+1;
	end;
            st:=(y2-y1)/10;
	    y4:=y2;
	    y3:=y1;
	if (y1>0) and (y2>0) Then
	    begin
		 y1:=-st;
	         y2:=y2+st;
	    end
	else if (y1<0) and (y2<0) then
	    begin
		 y2:=st;
		 y1:=y1-st;
	    end
	else
            begin
	         y1:=y1-st;
		 y2:=y2+st;
 	    end;

        setcolor (9);
        y0:=-y1/(y2-y1)*320+80;
        line(80,505-round(y0),560,505-round(y0));
        xx:=a;
        yy:=(5-2*xx);
        y:=(yy-y1)/(y2-y1)*320+80;
        line(80,505-round(y),80,505-round(y0));
        xx:=(560-80)/505*(b-a)+a;
        yy:=(5-2*xx);
        y:=(yy-y1)/(y2-y1)*320+80;
        line(560,505-round(y),560,505-round(y0));

        z:=y0;
        x:=80;
        while (x<=560) do
        begin
            xx:=(x-80)/505*(b-a)+a;
            yy:=(5-2*xx);
            y:=(yy-y1)/(y2-y1)*320+80;
            line(round(x)-1,505-round(z),round(x),505-round(y));
            z:=y;
            x:=x+1;
        end;

    setcolor(11);
    outtextxy(250, 40, 'Integral = ');
    S:=5*b-2/2*b*b-5*a+2/2*a*a;
    str(s:6:2, t);
    outtextxy(340, 40, t);
    setcolor(4);
    x:=-a/(b-a)*480+80;
    line(round(x), 120, round(x), 440);
    y:=-y1/(y2-y1)*320+120;
    line(80,520-round(y),560,520-round(y));
    setcolor(11);
    str(a:2:2,t);
	outtextxy(60,430,'a='+t);
	str(b:2:2,t);
	outtextxy(530,430,'b='+t);
	str(y4:2:2,t);
	outtextxy(280,60,'ymax='+t);
	str(y3:2:2,t);
	outtextxy(280,430,'ymin='+t);
        outtextxy(285,20,'y=5-2x');
        setcolor(10);
        outtextxy(235,455,'Nagmite lubuyu klavishu');
      	readkey;
	closegraph;
end;
{---------------------------}
begin
clrscr;
d:=1;
f:=1;
vibor(d);
repeat
          e:=readkey;
	  if e=chr(0) then
		 begin
		      e:=readkey;
		      case e of
			  chr(72):
				if d=1 then
				     d:=5
				else
				     d:=d-1;
			  chr(80):
				if d=5 then
				     d:=1
                                else
				     d:=d+1;
                                else   write ('nagata ne ta klavisha');
		      end;
                  end
	  else
		begin
		    case e of
			chr(27) : f:=0;
			chr(13) : case d of
					  1: o_programme;
					  2: vvod_predelov(a, b);
                                          3: raschet(a, b,s);
					  4: grafik;
                                          5: f:=0;
                                   end;
                    else
                          begin
                          gotoxy(15,20);
                          write('Ne ta klavisha,nagmite <Enter>');
                          readln;
                          end;
                    end;
                 end;
             vibor(d);
           until f=0;
end.