Problem:
Doubly Linked List

Your task is to implement a double linked list.

Write a program which performs the following operations:

insert x: insert an element with key x into the front of the list.

delete x: delete the first element which has the key of x from the list. If there is not such element, you need not do anything.

deleteFirst: delete the first element from the list.

deleteLast: delete the last element from the list.

Input

The input is given in the following format:

n

command1

command2

...

commandn

In the first line, the number of operations n is given. In the following n lines, the above mentioned operations are given in the following format:

insert x

delete x

deleteFirst

deleteLast

Output

Print all the element (key) in the list after the given operations. Two consequtive keys should be separated by a single space.

Constraints

The number of operations ≤ 2,000,000

The number of delete operations ≤ 20

0 ≤ value of a key ≤ 109

The number of elements in the list does not exceed 106

For a delete, deleteFirst or deleteLast operation, there is at least one element in the list.

Sample Input 1

7
insert 5
insert 2
insert 3
insert 1
delete 3
insert 6
delete 5

Sample Output 1

6 1 2

Sample Input 2

9
insert 5
insert 2
insert 3
insert 1
delete 3
insert 6
delete 5
deleteFirst
deleteLast

Sample Output 2

1

Solution in C++ (judge verdict: Memory Limit Exceeded)

#include <iostream>
#include <string>
#include <vector>
#include <cassert>

struct Proc{
    std::string meirei;
    int value;
};

typedef std::vector<Proc> ProVec;
typedef std::vector<int> IntVec;

int input(ProVec& vec);
int output(IntVec vec);
IntVec calc(ProVec vec);

int main()
{
	ProVec ivec; 
	input(ivec);
	IntVec ovec = calc(ivec);
//	IntVec ovec ;
//	for(int i =0; i < ivec.size();i++){
//		ovec.push_back(ivec[i].value);
//	}
	output(ovec);
	return 0;
}
///--------------------------------------------
int input(ProVec& vec)
{
	int n;
	std::cin >> n;
	vec.resize(n);
	for(int i = 0; i < vec.size(); i++){
		std::cin >> vec[i].meirei;
		if((vec[i].meirei == "deleteFirst")||(vec[i].meirei == "deleteLast")){
			continue;
		}
		std::cin >> vec[i].value;
	}
	return 0;
}
///--------------------------------------------
int output(IntVec vec)
{
	for(int i = 0; i < (vec.size()); i++){
		std::cout << vec[i] ;
		if(i < ((vec.size())-1)){
			std::cout << " " ; 
		}
	}
	std::cout << std::endl;
	return 0;
}
///--------------------------------------------
///@func    calc
///@brif    ?¨????
///--------------------------------------------
IntVec calc(ProVec vec)
{
	
	IntVec ovec;
	for(int i = 0; i < vec.size(); i++){
		if(vec[i].meirei == "insert"){
			ovec.insert(ovec.begin(), vec[i].value);
		}else if(vec[i].meirei == "delete"){
			int p = 0;
			while(true){
				if(ovec[p] == vec[i].value){
					break;
				}
				p++;
			    if(p == ovec.size()){
			    	break;
			    }
			}
            if(p != ovec.size()){
                ovec.erase(ovec.begin()+p);
            }    
    		
		}else if(vec[i].meirei == "deleteFirst"){
			ovec.erase(ovec.begin());
//log			std::cout << "deleteFirst" << std::endl;
		}else if(vec[i].meirei == "deleteLast"){
			ovec.pop_back();
//log			std::cout << "deleteLast" << std::endl;
		}else {
			assert(true);
		}
//std::cout << i << "::" ;
//		output(ovec);
	}
	return ovec;
}