// Harry Poter
#include <stdio.h>
#include <iostream>
#include <stdlib.h>
#include <string.h>
using namespace std;
int main()
{
    char line[200001], w2[200001];
    cin.getline(line, sizeof(line));
    int t = 0, i;

    for(i = 0; i < strlen(line); i++){
            if (line[i] == line[i + 1]) {
                i++;
A:    if (line[i + 1] != line[i + 2]) {
        if (t != 0 && w2[t - 1] == line[i + 1]) {t--; i += 1; goto A;}
                }
            }
    else {w2[t++] = line[i];}
        }
    w2[t] = '\0';
    printf("%s", w2);
}