#include<stdio.h>
#include<stdlib.h>
typedef struct node
{
    int data;
    struct node*next;
}Node;
Node*head=NULL,*tail;
void  create (int num)
{
    Node*newNode=(Node*)malloc(1*sizeof(Node));
    newNode->data=num;
    newNode->next=NULL;
    if(head==NULL)
    {
        head=newNode;
        tail=newNode;
    }
    else
    {
        tail->next=newNode;
        tail=newNode;
    }
}
int search(int x)
{
    Node *itr=head;
    int pos=1;
    while(itr!=NULL)
    {
        if(itr->data==x)
        return pos;
        itr=itr->next;
        pos++;
    }
    return -1;
    
}
int main()
{
    int n,i,num,x;
    scan("%d",&n);
    for(i=0;i<n;i++)
    {
    scanf("%d",&num);
    create(num);
    }
    scanf("%d",x);
    int ans=search(x);
    if(ans==-1)
    {
        printf("-1");
    }
    else
    {
        printf("%d",ans);
    }
}