Could anyone tell me why I always got WA?
Thank you.
Here is my program :

program N2 (input, output);
  var lX, lY, lK : longint;
      x, y : array [1.. 1000] of longint;
  function solve (lT : longint) : boolean;
    var lX1, lY1, lU, lV, lMax : longint;
    begin
      lU := 1000;
      lV := 1000;
      lX1 := lX;
      lY1 := lY;
      repeat
        x [lU] := lX1 mod lT;
        lX1 := lX1 div lT;
        lU := lU - 1;
      until lX1 = 0;
      repeat
        y [lV] := lY1 mod lT;
        lY1 := lY1 div lT;
        lV := lV - 1;
      until lY1 = 0;
      lU := lU + 1;
      lV := lV + 1;
      lMax := 1001 - lV;
      for lX1 := lU to 1000 do
        if y [lV] = x [lX1] then
          begin
            lMax := lMax - 1;
            lV := lV + 1;
          end;
      if lMax = 0 then solve := true
                  else solve := false;
    end;
  begin
    readln (lX, lY);
    lK := 2;
    repeat
      if solve (lK) = true then
        begin
          writeln (lK);
          halt;
        end;
      lK := lK + 1;
    until lK > lX;
    writeln ('No solution');
  end.