#include <stdio.h>
#include <stdlib.h>

struct Node{
    int data;
    struct Node* left;
    struct Node* right;
};

struct Node* createNode(int data){
    struct Node* newNode = (struct Node*)malloc(sizeof(struct Node));
    if (! newNode) {
        printf("memory allocation failed\n");
        exit(1);

    }
    
    newNode->data = data;
    newNode->left = newNode->right = NULL;
    return newNode;
}

struct Node* insert(struct Node* root, int data){
    if (root == NULL)
        return createNode(data);
    if (data < root -> data)
        root->right == insert(root->left, data);
    else if (data > root->data)
        root-> right = insert(root->right, data);
    return root;
    }
    
int search(struct Node* root, int target) {
    if (root == NULL)
        return 0;
    if (root->data == target)
        return 1;
    else if (target < root->data)
        return search(root->left,target);
    else 
        return search(root->right, target);
}

int main(){
    int n,value , target;
    scanf("%d",&n);
    
    if(n <= 0){
        printf("invalid input\n");
        return 0;
    }
    
    struct Node* root = NULL;
    for (int i =0,i < n; i++){
        scanf("%d", &value);
        root = insert (root, value);
    }
    
    scanf("%d", &target);
    
    if (target < 0){
        printf("invalid input\n");
        return 0;
    }
    
    if (search(root, target))
       printf("found\n");
    else 
       printf("not found\n");
    return 0;
}