static void shellsort(int a[], int n) {
		for (int gap = n / 2; gap >= 1; gap /= 2) {
			for (int i = gap; i < n; i++) {
				if (a[i] < a[i - gap]) {
					int temp = a[i];
					int k = i - gap;
					while (k >= 0 && a[k] > temp) {
						a[k + gap] = a[k];
						k -= gap;
					}
					a[k + gap] = temp;
				}
			}
		}
	}