public static int[] mergeSort(int[] array,int start,int end){
		if(end - start >0){               //should >0
			int mid = (start+end) / 2;
			mergeSort(array,start,mid);   // sort left
			mergeSort(array,mid+1,end);     //  right mid need  add 1
			merge(array,start,mid,end);     // there do not add 1
		}
		return array;
	}