이분검색

import sys

sys.stdin = open("input.txt","rt")

a,b = map(int, input().split())

nums = list(map(int, input().split()))
nums.sort()

lt = 0
rt = a-1

mid = (lt + rt)//2

while True:
    mid = (rt+lt)//2

    if nums[mid] > b:
        rt = mid - 1

    elif nums[mid] < b:
        lt = mid + 1

    elif nums[mid] == b:
        print(mid+1)
        break