Xiaoxu has two small sticks, one is 4cm long and the other is 8cm long. He has to take another small stick of how many centimeters long to form a triangle.
小旭有两根小棒，一根长4cm，一根长8cm，他必须再拿一根长多少cm的小棒，才能围成一个三角形．
<result>5</result>