There are 104 students in classes A and B, 106 students in classes B and C, and 101 students in classes C and D. How many people are there in Class A and Class D?
甲、乙两班共有学生104人，乙、丙两班共有学生106人，丙、丁两班共有学生101人．甲、丁两班共有多少人？
<gadget id="calculator">101 - 106</gadget>
<output>-5</output>

<gadget id="calculator">104 + (-5)</gadget>
<output>99</output>

<result>99</result>