/**
 * @param a A list of items
 * @param b An item to search its index inside the list of items
 */
function binarySearch(a, b) {
  for (var c = 0, d = a.length, e; c <= d;) {
    e = ~~((d + c) / 2);
    if (a[e] === b) return e;
    a[e] > b ? d = e - 1 : c = e + 1
  }
  return -1;
}