There are several hats in a box, all but three are red, all but four are blue, all but four are yellow, all but four are white, the box How many hats are there in total?
一个箱子里放了若干顶帽子，除3顶外其余都是红的，除4顶外其余都是蓝的，除4顶外其余都是黄的，除4顶外其余都是白的，箱子里一共有多少顶帽子？
<gadget id="calculator">3 + 4 + 4 + 4</gadget>
<output>15</output>

<result>15</result>