const rl = require("readline").createInterface({ input: process.stdin });
var iter = rl[Symbol.asyncIterator]();
const readline = async () => (await iter.next()).value;
void async function () {
// Write your code here
while(line = await readline()){
let tokens = line.split(' ').map(a=>parseInt(a)).sort((a,b)=>a-b);
console.log(2*tokens[1]-tokens[0]);
}
}()
这题真是莫名其妙的……

京公网安备 11010502036488号