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

int binary_search(int a[], int n, int x){
    int left = 0;           
    int right = n - 1;     
    
    while (left <= right) {
        int mid = (left + right) / 2; 
        
        if (a[mid] == x) {
            return mid;      
        } else if (a[mid] < x) {
            left = mid + 1; 
        } else {
            right = mid - 1; 
        }
    }
    
    return -1; 
}

int main(void) {
    int n, x, i;
    int *a;
    int ans = -1;
    
    if (scanf("%d %d", &n, &x) != 2) return -1;
    
    a = (int*)malloc(sizeof(int) * n);
    if (a == NULL) {
        printf("ERROR\n");
        return -1;
    }
    
    for (i = 0; i < n; i++) {
        scanf("%d", &a[i]);
    }
    
    ans = binary_search(a, n, x);
    
    if (ans != -1) {
        printf("a[%d] = %d\n", ans, a[ans]);
    } else {
        printf("not found\n");
    }
    
    free(a);
    return 0;
}