function convertToBinary(num) {
        let a = num;
        let res = "";
        while (a >= 1) {
          res = (a % 2) + res;
          if (a % 2) a--;
          a /= 2;
        }
        // console.log(res);
        for (let i = 8 - res.length; i; --i) res = 0 + res;
        return res;
      }