#include <stdio.h> #include<malloc.h> int main() { int times ; scanf("%d",×); int queue[100000]; int head =0; int tail = 0; for(int i=0;i<times;i++){ char* op = (char*)malloc(sizeof(char)*6); scanf("%s",op); if(!strcmp(op,"push")){ int tmp; scanf("%d",&tmp); queue[tail++] = tmp; } if(!strcmp(op,"pop")){ if(tail<=head){ printf("error\n"); }else{ printf("%d\n",queue[head++]); } } if(!strcmp(op, "front")){ if(tail<=head){ printf("error\n"); } else{ printf("%d\n",queue[head]); } } } return 0; }