杭电1007为什么不能AC

#include <iostream>
#include <cstdlib>
#include <functional>
#include <algorithm>

using namespace std;

int main()
{
     int n;
    int i,j;
     int a[100];
    int flag;
     while(scanf("%d",&n)!=EOF)
     {
        if(n<1)
            continue;
        flag=1;
        for( i=0;i<n;i++)
          cin>>a[i];
        sort(a,a+n);
        for( j=n-1,  i=0;j>=i;i++,j--)
        {
            if(flag==0)
                cout<<' ';
            cout<<a[j];
            if(i<j)
                cout<<' ';
                if(i!=j)
                    cout<<a[i];
           flag=0;

        }
        cout<<endl;
    }
     return 0;
}