SYSTEM READY
function mergeSort(arr, l, r) {  if (l >= r) return;  const m = l + Math.floor((r - l) / 2);  mergeSort(arr, l, m);  mergeSort(arr, m + 1, r);  merge(arr, l, m, r);} function merge(arr, l, m, r) {  // Copy data to temp arrays  // Merge back to arr[l..r]}