void intersection(Menge a) {  
		int j = 0;
		int[] tmp;
		
		if(this.elements.length >= a.elements.length)
			tmp = new int[this.elements.length];
		else 		
			tmp = new int[a.elements.length]; 
		
		for (int i = 0; i < a.elements.length; i++) {
			if(isElement(a.elements[i])) {
					tmp[i] = a.elements[i];
					System.out.println("tmp"+i +" " + tmp[i]);
					j++;
			}
			
		}

		this.elements = new int[4];
		for(int i = 0; i < 4; i++) {
			this.elements[i] = tmp[i];
		}
	}