#include<iostream>
using namespace std;

int linearSearch(int arr[], int n, int key) {
    for (int i=0; i<n; i++) {
        if (arr[i]==key) {
            return i;
        }
    }
    return -1;
}

int main() {

    int n;
    cin>>n;

    int arr[n];

    for (int i=0; i<n; i++) {
        cin>>arr[i];
    }

    int key;
    cin>>key;

    cout<<linearSearch(arr, n, key)<<endl;

    return 0;

}