1.2 KB | 1188 chars
#include <iostream>
#include <deque>
#include <string>
using namespace std;
int N;
string a;
int b;
deque <int> Q;
int main() {
ios::sync_with_stdio(0);
cin.tie(0);
cin >> N;
for(int q = 0; q< N; q++) {
cin >> a;
if(a == "push") {
cin >> b;
Q.push_back(b);
}
else if(a == "pop") {
if(Q.empty()) {
cout << "-1\n";
}
else {
cout << Q.front() <<"\n";
Q.pop_front();
}
}
else if(a == "size") {
cout << Q.size() << "\n";
}
else if(a == "empty") {
if(Q.empty()) {
cout << "1\n";
}
else {
cout << "0\n";
}
}
else if(a == "front") {
if(Q.empty()) {
cout << "-1\n";
}
else {
cout << Q.front() <<"\n";
}
}
else if(a == "back") {
if(Q.empty()) {
cout << "-1\n";
}
else {
cout << Q.back() <<"\n";
}
}
}
}