Cipher Message

http://acm.hust.edu.cn/vjudge/contest/view.action?cid=34121#problem/C

// File Name: c.cpp
// Author: bo_jwolf
// Created Time: 2013年10月16日 星期三 16:08:12

#include<vector>
#include<list>
#include<map>
#include<set>
#include<deque>
#include<stack>
#include<bitset>
#include<algorithm>
#include<functional>
#include<numeric>
#include<utility>
#include<sstream>
#include<iostream>
#include<iomanip>
#include<cstdio>
#include<cmath>
#include<cstdlib>
#include<cstring>
#include<ctime>

using namespace std;
stack< char > Q;
stack< char >P;

int main(){
	char temp;
	while( cin >> temp ){
		if( Q.empty() || Q.top() != temp ){
			Q.push( temp );
		}
		else{
			Q.pop();
		}
	}
	while( Q.size() ){
		P.push( Q.top() );
		Q.pop();
	}
	while( P.size() ){
		cout << P.top();
		P.pop();
	}
	cout << endl;
return 0;
}