void mergeArray(int arr1[], int n, int arr2[], int m, int arr3[]) {
  int i, j, k;
  i = j = k = 0;
  while (i < n && j < m) {
    if (arr1[i] < arr2[j]) {
      arr3[k] = arr1[i];
      k++;
      i++;
    } else {
      arr3[k] = arr2[j];
      k++;
      j++;
    }
  }
  while (i < n) {
    arr3[k] = arr1[i];
    i++;
    k++;
  }
  while (j < m) {
    arr3[k] = arr2[j];
    k++;
    j++;
  }
}