//第3回 課題１
#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;
		//printf("%d %d %d :%d\n",lef,mid,rig,a[mid]);

		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;
	scanf("%d %d",&n,&x);
	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;
}