Aliens

#include <iostream>
#include <vector>
#include <cstdio>
#include <cmath>
#include<algorithm>
#define FOR(i,l,r) for (int i=l;i<r;i++)
#define FORx(i,l,r,x) for (int i=l;i<r;i+=x)
#define FORD(i,r,l) for (int i=r;i>=l;i--)
#define FORDx(i,r,l,x) for (int i=r;i>=l;i-=x)
#define EL '\n'
using namespace std;
#define fastio  ios_base::sync_with_stdio(0);cin.tie(NULL);

int main() {
    fastio;
    string x;
    cin>>x;
    string tmp;
    int len=x.length();
    for(int i=0;i<len;i++){
        if(x[i]!='R'){
            if(tmp.back()==x[i]){
                tmp.pop_back();
            }
            else{
                tmp.push_back(x[i]);
            }
        }
        else if(x[i]=='R'){
            if(!tmp.empty())reverse(tmp.begin(),tmp.end());
        }
    }
    cout<<tmp<<EL;
}