import math
import sys
def S(): return sys.stdin.readline().rstrip()
def I(): return int(sys.stdin.readline().rstrip())
def MI(): return map(int, sys.stdin.readline().rstrip().split())
def LI(): return list(map(int, sys.stdin.readline().rstrip().split()))
def LS(): return list(sys.stdin.readline().rstrip().split())

n, k = MI()
s = S()

lq = []
d = {}

for i in range(n):
    if s[i] == "(":
        lq.append(i+1)
    else:
        d[i+1] = lq.pop(-1)
        d[d[i+1]] = i+1

print(d[k])