HDU 1702 ACboy needs your help again!(스택 및 큐)

#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <algorithm>
#include <queue>
#include <stack>
#include <map>
#include <cstring>
#include <climits>
#include <cmath>
#include <cctype>

using namespace std;

char a[10];

int main()
{
    int t,n,i,x,y;
    scanf("%d",&t);
    while(t--)
    {
        scanf("%d%s",&n,a);
        if(strcmp(a,"FIFO") == 0)
        {
            queue<int> q;
            for(i=0; i<n; i++)
            {
                scanf("%s",a);
                if(strcmp(a,"IN") == 0)
                {
                    scanf("%d",&x);
                    q.push(x);
                }
                else
                {
                    if(q.empty())
                        printf("None
");
                    else
                    {
                        y = q.front();
                        q.pop();
                        printf("%d
",y);
                    }
                }
            }
        }
        else
        {
            stack<int> s;
            for(i=0; i<n; i++)
            {
                scanf("%s",a);
                if(strcmp(a,"IN") == 0)
                {
                    scanf("%d",&x);
                    s.push(x);
                }
                else
                {
                    if(s.empty())
                        printf("None
");
                    else
                    {
                        y = s.top();
                        s.pop();
                        printf("%d
",y);
                    }
                }
            }
        }
    }
    return 0;
}