#include<iostream>
#include<string.h>
#include<stdio.h>
using namespace std;
int main()
{
    char in[200000];
    int num ;
    char c;
    scanf("%c",&c);
    char nc = c;
    if(c == '\n')
    goto end;
    in[0] = c;
    for(num=1;;num++)
    {
        scanf("%c",&c);
        if(c == '\n')
        break;
        if(nc == c)
        {
           in[num-1] = '\0';
           num -= 2;
           if((num+1) != 0)
            nc = in[num];
                   else
                        nc = '\0';

        }
        else
        {
           in[num] = c;
           nc = c;
        }

    }
end:
        for(int i=0;i<=num;i++)
    cout << in[i];

}