#coding: UTF-8

import sys
from math import pi
from collections import deque
from functools import reduce

### defs ###

### main ###
N,K = map(int,sys.stdin.readline().split())
S = sys.stdin.readline()[:N]

sz = len(S)
idx = [-1]*sz
stack = []
for i in range(sz):
	if(S[i]=='('):
		stack.append(i)
	else:
		hd = stack[-1]
		idx[i] = hd
		idx[hd] = i
		stack.pop()
print(idx[K-1]+1)