Problem:
Score : 200 points

Problem Statement

Sig has built his own keyboard. Designed for ultimate simplicity, this keyboard only has 3 keys on it: the 0 key, the 1 key and the backspace key.

To begin with, he is using a plain text editor with this keyboard. This editor always displays one string (possibly empty). Just after the editor is launched, this string is empty. When each key on the keyboard is pressed, the following changes occur to the string:

The 0 key: a letter 0 will be inserted to the right of the string.

The 1 key: a letter 1 will be inserted to the right of the string.

The backspace key: if the string is empty, nothing happens. Otherwise, the rightmost letter of the string is deleted.

Sig has launched the editor, and pressed these keys several times. You are given a string s, which is a record of his keystrokes in order. In this string, the letter 0 stands for the 0 key, the letter 1 stands for the 1 key and the letter B stands for the backspace key. What string is displayed in the editor now?

Constraints

1 ≦ |s| ≦ 10 (|s| denotes the length of s)

s consists of the letters 0, 1 and B.

The correct answer is not an empty string.

Input

The input is given from Standard Input in the following format:

s

Output

Print the string displayed in the editor in the end.

Sample Input 1

01B0

Sample Output 1

00

Each time the key is pressed, the string in the editor will change as follows: 0, 01, 0, 00.

Sample Input 2

0BB1

Sample Output 2

1

Each time the key is pressed, the string in the editor will change as follows: 0, (empty), (empty), 1.

Solution in C++14 (GCC 5.4.1) (judge verdict: Wrong Answer)

#include<bits/stdc++.h>
using namespace std;


/// File input & output /////
#define fRead(x)        freopen("x.txt","r",stdin)
#define fWrite(x)       freopen ("x.txt","w",stdout)


#define ld              long double
#define ll              long long
#define ull             unsigned long long
#define ff              first
#define ss              second
#define pb              push_back
#define INF             2e16
#define PI              acos(-1.0)
#define mp              make_pair
#define pii             pair<int,int>
#define pll             pair<LL,LL>


#define min3(a,b,c)     min(a,min(b,c))
#define max3(a,b,c)     max(a,max(b,c))
#define min4(a,b,c,d)   min(a,min(b,min(c,d)))
#define max4(a,b,c,d)   max(a,max(b,max(c,d)))
#define SQR(a)          ((a)*(a))
#define FOR(i,a,b)      for(int i=a;i<=b;i++)
#define ROF(i,a,b)      for(int i=a;i>=b;i--)
#define REP(i,b)        for(int i=0;i<b;i++)
#define MEM(a,x)        memset(a,x,sizeof(a))
#define ABS(x)          ((x)<0?-(x):(x))

#define SORT(v)         sort(v.begin(),v.end())
#define REV(v)          reverse(v.begin(),v.end())


#define FASTIO        ios_base::sync_with_stdio(0);cin.tie(nullptr);




///..................Sort by second element in a pair in decending order............. ///
bool SortbySecDesc(const pair<long long,long long > &a, const pair<long long,long long > &b)
{
    return a.second>b.second;
}

///.........................first element of pair in descending order..........................//////
bool sortinrev(const pair<int,int> &a,
               const pair<int,int> &b)
{
       return (a.first > b.first);
}



///.............................................................TEMPLATE................................................./////

int main()
{
    FASTIO;

    string st;

    cin >> st;

    stack<char>s;


    for(int i=0; i<st.length();i++)
    {
        if(st[i]=='0' || st[i]=='1')
        {
            s.push(st[i]);
        }
        else if(st[i]=='B')
        {
            if(s.empty())
            {
                continue;
            }
            else
            {
                s.pop();
            }
        }
    }

    while(!s.empty())
    {
        cout << s.top();
        s.pop();
    }





    return 0;
}