import sys
import math
from math import sin, cos, tan
from functools import reduce
from collections import deque
import heapq
sys.setrecursionlimit(1000000)
intm1 = lambda x:int(x)-1

N, K = map(int,input().split())
K -= 1
S = input()

cnt = 1 if S[K] == '(' else -1
for i in range(K + 1, N, 1) if S[K] == '(' else range(K - 1, -1, -1):
	cnt += 1 if S[i] == '(' else -1
	if cnt == 0:
		print(i + 1)
		break