864 B | 864 chars
#include <iostream>
#include <queue>
#include <stdio.h>
using namespace std;
int n;
char ar[10];
int main()
{
queue <int> qu;
scanf("%d",&n);
for(int x=0; x<n; x++)
{
for(int y=0; y<10; y++)ar[y]='0';
scanf("%s",ar);
if(ar[0]=='p')
{
if(ar[1]=='o')//pop
{
if(qu.empty()) printf("-1\n");
else
{
printf("%d\n",qu.front());
qu.pop();
}
}
else //push
{
int a;
scanf("%d\n",&a);
qu.push(a);
}
}
else if(ar[0]=='f') //front
{
if(qu.empty()) printf("-1\n");
else
{
printf("%d\n",qu.front());
}
}
else if(ar[0]=='b') //back
{
if(qu.empty()) printf("-1\n");
else
{
printf("%d\n",qu.back());
}
}
else if(ar[0]=='s') //size
{
printf("%d\n",qu.size());
}
else if(ar[0]=='e')
{
if(qu.empty()) printf("1\n");
else printf("0\n");
}
}
}