题解 | 【模板】队列

import collections
import sys

# for line in sys.stdin:
#     a = line.split()
#     print(int(a[0]) + int(a[1]))

def  solver():
    n =int(input())
    cmd_list=[]
    def func(cmd):
        if "push" in cmd:
            cmds=cmd.split(" ")
            queue.append(cmds[1])
        elif "pop" in cmd:
            if len(queue)==0:
                print("error")
            else:
                print(queue.popleft())
        elif "front" in cmd: 
            if len(queue)==0:
                print("error")
            else:
                print(queue[0])

    for i in range(n):
        cmd_list.append(input())
    queue=collections.deque()
    for i in range(len(cmd_list)):
        func(cmd_list[i])

    
solver()