void insertSort(int a[], int length)
{
    int begin = 0;
    int value;
    int j;
 
    for (int i = 1; i < length; ++i) {
        value = a[i];
 
        for (j = i - 1; j >= begin && a[j] > value; --j) {
            a[j + 1] = a[j];
        }
 
        a[j + 1] = value;
    }
}