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
// 方1 使用正则,会超时
let line = await readline();
// let str = '';
// while(str!==line){
// str = line;
// line = line.replace(/([a-z])\1{1}/g,'')
// }
// console.log(str?str:0)
//方2,遍历一次的方式
let arr = [];
line = line.split('');
let len = line.length;
arr[0] = line[0];
for(let i =1;i<len;i++){
if(line[i]===arr[arr.length-1]){
arr.pop()
}else{
arr.push(line[i])
}
}
console.log(arr.length?arr.join(''):0)
}()