program xxx;
 uses crt;
 label 1;
 const z=0.000001;
 var
   A,B,C,D,w, kood:integer;
   y,x,x3,x4,e,r,F,k,s,l,h,j,u,n,x1,x2,p,g,o,m:real;
   ch:char;
   ps, sx:string;
  procedure str1;
     begin
         p:=A*x1*x1*x1+B*x1*x1+C*x1+D;
         g:=A*h*h*h+B*h*h+C*h+D;
         o:=A*x2*x2*x2+B*x2*x2+C*x2+D;
         m:=A*j*j*j+B*j*j+C*j+D;
     end;
  procedure str2;
     begin
         u:=A*n*n*n+B*n*n+C*n+D;
     end;
       begin
          repeat
         clrscr;
        writeln('Enter password.');
        readln(ps);
        if ps<>'xxx' then
           begin
           textmode(CO40);
             for w:=1 to 2 do
               begin
                 clrscr;
                 gotoxy(15,12); write('NO ACCESS!');write(^G);
                 clrscr;
                 write(' ');write(^G);
               end;
           end;
           textmode(CO80);
          until ps='xxx';

        begin
          repeat
            clrscr;
            1: writeln('Введите A,B,C,D.(коэффициенты кубического уравнения)');
            writeln;
            {readln(sx);
            val(copy(sx, 1, pos(' ',sx)), b, kood);
            delete(sx, 1, pos(' ', sx)+1);
            val(copy(sx, 1, pos(' ', sx)), c, kood);
            delete(sx, 1, pos(' ', sx)+1);
            val(sx, d, kood);}
          {$I-}
            readln(A,B,C,D);
          {$I+}
            if (IOResult<>0) or (A=0) then

                begin
                  clrscr;writeln('Ошибка при вводе коэффициентов.');goto 1;
                end;

            randomize;
            h:=-1000; j:=1000;
            k:=3*A; s:=2*B; l:=C; e:=2*k;
            F:=s*s-4*k*l;
            writeln;
            writeln('Ds=',F:5:2);
            if F>=0 then
                begin
                    r:=sqrt(F);
                    x3:=(-s+r)/e; x4:=(-s-r)/e;
                    if x3>x4 then
                       begin
                          x1:=x4; x2:=x3;
                       end
                    else
                       begin
                          x1:=x3; x2:=x4;
                       end;
                    writeln;
                    writeln('Критические точки.');
                    writeln('X1=',x1:5:2,' X2=',x2:5:2); str1;
                    writeln('F(X1)=',p:5:2,' F(X2)=',o:5:2);
                end
            else
                begin
                    x1:=-(random(30)+10);
                    x2:=random(30)+10;
                    writeln('X1r=',x1:5:2,' X2r=',x2:5:2);
                end;
                   begin
                       str1;
                       writeln;
                       writeln('Корни уравнения.');
                       if p=0 then writeln('Xst=',x1:3:5);
                       if o=0 then writeln('Xst=',x2:3:5);
                       if (g*p)<0 then
                           begin
                              x:=x1;

                                      repeat
                                        n:=(x+h)/2;str2;
                                        if (abs(u)>z) and ((p*u)<0) then h:=n else x:=n;
                                      until abs(u)<z;

                               writeln('X-=',n:3:5);
                           end;
                       if (o*m)<0 then
                           begin
                              x:=x2;

                                      repeat
                                        n:=(x+j)/2;str2;
                                        if (abs(u)>z) and ((o*u)<0) then j:=n else x:=n;
                                      until abs(u)<z;

                               writeln('X+=',n:3:5);
                           end;
                        if (p*o)<0 then
                           begin
                              x:=x1; y:=x2;

                                      repeat
                                        n:=(x+y)/2; str2;
                                        if (abs(u)>z) and ((o*u)<0) then x:=n else y:=n;
                                      until abs(u)<z;

                               writeln('Xo=',n:3:5);
                           end;

        end;
      writeln;
      writeln('Завершить программу? y/n');
      readln(ch);
      until (ch='y') or (ch='д') or (ch='Y') or (ch='Д');
       end;

end.  {ALL RIGHTS RESERVED}