10845

#include <iostream>

#include <stdio.h>

#include <string.h>

#include <queue>

using namespace std;

int main()

{

int T = 0;

cin >> T;

queue<int> Q;

while (T--)

{

char cmd[10];

cin >> cmd;

if (!strcmp(cmd, "push"))

{

int num;

cin >> num;

Q.push(num);

}

else if (!strcmp(cmd, "pop"))

{

if (!Q.empty())

{

int tmp = Q.front();

cout << tmp << endl;

Q.pop();

}

else cout << -1 << endl;

}

else if (!strcmp(cmd, "front"))

{

if (Q.empty()) cout << -1 << endl;

else cout << Q.front() << endl;

}

else if (!strcmp(cmd, "back"))

{

if (Q.empty()) cout << -1 << endl;

else cout << Q.back() << endl;

}

else if (!strcmp(cmd, "size"))

{

cout << Q.size() << endl;

}

else if (!strcmp(cmd, "empty"))

{

if (Q.empty()) cout << 1<<endl;

else cout << 0<<endl;

}

}

system("pause");

return 0;

}