You need to write a program to simulate a queue of names. Each name is a string consisting of English letters only. There are three operations:
1. “Push [name]”, which means to enque name in the queue.
2. “Pop”, which means to deque. If the queue is empty, this operation takes no effect.
3. “Front”, which means to print out the name in the front of queue. If the queue is empty, print "empty" (without quotes).
There will be at most 107 operations. Each line contains one of the following operations. “Push [name]” (without quotes), “Pop” (without quotes), “Front”(without quotes). The length of each name is at most 20.
Case 1 : at most 103 operations
Case 2 : at most 105 operations
Case 3 : at most 107 operations
Case 4 : at most 107 operations
For each “Front” operation, print out the name in the front of the queue.