15, 16, 17, ... 97 are written on the blackboard, a total of 83 numbers. Erase two numbers at will each time, and then write the difference between the sum of these two numbers and minus 1. For example, when erasing 16 and 80, write 95. After several times, there will be only one number left on the blackboard. What is this number?
黑板上写着15，16，17，…97共83个数，每次任意擦去两个数，再写上这两个数的和减1的差，例如擦掉16和80，要写上95，经过若干次后，黑板上就会只剩下一个数，这个数是多少．
<gadget id="calculator">15 + 97</gadget>
<output>112</output>

<gadget id="calculator">83 / 2</gadget>
<output>83/2 = around 41.5</output>

<gadget id="calculator">112 * (83/2)</gadget>
<output>4_648</output>

<gadget id="calculator">4_648 - 82</gadget>
<output>4_566</output>

<result>4_566</result>