#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;
    }
}
void display(int val){
    node *ptr=head;
    int pos=1;
    int found=0;
    while(ptr!=NULL){
        if(ptr->data==val){
            printf("%d",pos);
            found=1;
            break;
        }
        ptr=ptr->next;
        pos++;
    }
   if(!found){
       printf("-1\n");
   
    }
}
int main(){
    int s,i,n,val;
    scanf("%d",&s);
    for(i=0;i<s;i++){
        scanf("%d",&n);
        create(n);
    }
    scanf("%d",&val);
    
    display();
    return 0;
    
}