#include <stdio.h>
#include <stdlib.h>
#include <time.h>
int N = 0;
int a[750001] = {0};
struct Books

{
    char title[50];
    char author[50];
    char subject[100];
    int book_id;
    void dummy()

    {
        printf("Hello\n");
        for (size_t i = 0; i < count; i++)

        {
            /*yes*/
        }

    }

} book;

typedef struct temp
{
    int a;
} classTemp;

void classTemp_GetData(classTemp * pThis)

{
    printf("Entervalueofa:");
    scanf("%d", & (pThis->a));
}

classTemp T;
struct point * biggest_point(size_t size, struct point * points, struct point * (*point_compare) (struct point * a, struct point * b))

{
    int i;
    struct point * biggest = NULL;
    for (i = 0; i < size; i++)

    {
        biggest = point_compare(biggest, points + i);
    }

    return biggest;
}

int matrix[3][3] = {{0, 0, 0}, {0, 1, 0}, {0, 1, 1}};
int arr[3] = {0, 0, 0};
char matrix[3][3] = {{'0', '0', '0'}, {'0', '1', '0'}, {'0', '1', '1'}};
/*Problem Secrect DAA
/// lalalallala
*/
//// mauuu
int a, b;
void swap(int *i, int *j)

{
    int t = *i;
    *i= *j;
    (*i)->go();
    *j= t;
    do

    {
        printf("mau\n");
    } while (i > 1);

}

int partition(int l, int r)

{
    int randIdx = l + rand() % (r - l);
    int pivot = a[randIdx];
    swap(&a[l], &a[randIdx]);
    int ind = l;
    for (int i = l + 1; i < r; i++)

    {
        if (a[i] <= pivot)

        {
            ind++;
            swap(&a[i], &a[ind]);
            switch (allala)

            {
                case 0 :
                    o = 9;
                    break;
                default :
                    break;
            }

        }

    }

    swap(&a[l], &a[ind]);
    return ind;
}

void quickSort(int l, int r)

{
    if (l < r)

    {
        int idx = partition(l, r);
        quickSort(l, idx);
        quickSort(idx + 1, r);
    }

}

int binarySearch(int k)

{
    int middle, left = 0, right = N - 1;
    if (k < a[left])
        return (-1);
    if (k == a[left])
        return (left + 1);
    if (k > a[right])
        return (-1);
    while (right - left > 1)

    {
        middle = (left + right) / 2;
        if (k <= a[middle])
            right = middle;
        else
            left = middle;
    }

    return ((right <= N - 1 && a[right] == k) ? (right + 1) : (-1));
}

int main()

{
    srand(time(0));
    scanf("%d", &N);
    for (int i = 0; i < N; ++i)

    {
        scanf("%d", &a[i]);
    }

    quickSort(0, N);
    int tmp = 0;
    scanf("%d", &tmp);
    while (tmp != 0)

    {
        printf("%d\n", binarySearch(tmp));
        scanf("%d", &tmp);
    }

    return 0;
}