{program jacobi;       Shell for the function Jacobi}
{$N+,E+}
uses CRT, nothy;
{$I GetInput.i }

var
P, Q,
t
               :  comp;
x              :  extended;
code,
i,
J,                         {The Jacobi symbol}
x0,
y0
               :  integer;
InputOk        :  Boolean;

begin
  InputOk := False;
  if (ParamCount = 2)
  then
    begin
      InputOk := True;
      Val(ParamStr(1), x, code);
      if (frac(x) = 0) and (code = 0)
         and (x > -MaxAllow) and (x < MaxAllow)
      then P := x
      else InputOk := False;
      Val(ParamStr(2), x, code);
      t := x/2;
      if (frac(x) = 0) and (code = 0)
          and (x > 0) and (x < MaxAllow) and (2*t <> x)
      then Q := x
      else InputOk := False;
    end;
  if not InputOk
  then
    begin
      WriteLn('Will compute the Jacobi symbol (P/Q).');
      P := GetInput(WhereX, WhereY, '    Enter P = ',
                    '       (|P| ó 999999999999999999)',
                    -MaxAllow+1, MaxAllow-1);
      x0 := WhereX;
      y0 := WhereY;
      repeat
        Q := GetInput(x0, y0, 'Enter odd Q = ',
                      '     (1 ó Q ó 999999999999999999)', 1, MaxAllow-1);
        t := Q/2
      until Q <> 2*t;
      for i := 1 to 3 do
        begin
          GoToXY(1, WhereY - 1);
          ClrEoL
        end
    end;
  J := Jacobi(P, Q);
  WriteLn('(', P:1:0, '/', Q:1:0, ') = ', J:1)
end.