public void push (int x, int numStack) {
		if (numStack < 0 || numStack >2) {
			System.out.println ("Please input a valid numPointer");
		}
		else {
			if (size[numStack] < MAX_SIZE) {
				data[numStack*MAX_SIZE + size[numStack]] = x;
				size[numStack] ++;
			}
		}
	}