function countCounterfeit - serialNumber

function countCounterfeit(serialNumber) {

  // Write your code here

  let unique = (str) => {

    let strArr = str.split("");

    return strArr[0] !== strArr[1] && strArr[1] !== strArr[2];

  };

  var patt = new RegExp("([A-Z]+)([0-9]{4})([0-9]+)([A-Z]+)");

   var bill = 0;

   var validNotes = ["10","20","50","100","200","500","1000"];

    serialNumber.forEach(el => {

      var res = patt.exec(el); 

      if(res 

        && el.length >= 10 && el.length <= 12

        && res[1].length === 3 && unique(res[1]) 

        && res[4].length === 1 

        && validNotes.indexOf(res[3]) > -1

        && (parseInt(res[2]) >= 1900 && parseInt(res[2]) <= 2019)

       ){

        bill = bill + parseInt(res[3]);

      }

    });

  return bill;

}