Задачи
Книжная полка
include <bits/stdc++.h>
define ll long long
define ld long double
using namespace std; int main(){
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
ll n;
cin>>n;
deque<ll>dq;
for(int i = 0; i<n; i++){
ll m, k;
cin>>m;
if(m == 1 || m == 2){
cin>>k;
if(m == 1){
dq.push_front(k);
}
else if(m == 2){
dq.push_back(k);
}
}
if(m == 3){
cout<<dq.front()<<endl;
dq.pop_front();
}
else if(m == 4){
cout<<dq.back()<<endl;
dq.pop_back();
}
}
}