#include <stdio.h>

int main() {
    int n,key;
  
    scanf("%d",&n);
    int arr[n];
    for(int i=0;i<n;i++){
        scanf("%d",&arr[i]);
        scanf("%d",&key);
        int low=0,high=n-1,found=0;
        while(low<=high){
            int mid=(low+high)/2;
            if(arr[mid]==key){
                printf("element found at index %d\n",i);
                found=1;
                break;
            }
            else if(arr[mid]<key){
                low=mid-1;
            }
            else{
                high=mid-1;
            }
        }
        if(!found)
        printf("elements not found\n");
    }
    return 0;
}