#include <stdio.h>

int main() 
{
    int n,key,first,last,mid;
    int found=0;
    scanf("%d",&n);

    int arr[n];
    for(int i=0;i<n;i++)
    {
        scanf("%d",&arr[i]);
    }
//binary search
    scanf("%d",&key);
    first=1;
    last=n-1;
    while(first<=last)
    {
        mid=(first+last)/2;
    }
    if(arr[mid]==key)
    {
        printf("the element is found at:%d",i);
    }
    else if(arr[mid]<key)
    {
        first=mid+1;
    }
    else
    {
        last=mid-1;
    }
    if(!found)
    {
        printf("the element is not found");
    }
}