public static int ex_eculid(int a,int b) {
		if (b>a) {
			return ex_eculid(b, a);
		}
		
		//ԪʱܵõҪmod aõ
		int result = sub_ex_eculid(a, b, 1, 0, 0, 1, 0);
		if (0>result) {
			result = result - (result/a-1)*a;
		}
		
		return result;
	}