#include <stdio.h>
int main() {
    int n;
    int key;
    scanf("%d",&n);
    int arr[100];
    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("element not found\n");
return 0;
}