import sys, math
sys.set_int_max_str_digits(0)

N, K = map(int, input().split())
S = input()
stack = []
taiou = [0]*(N + 1)
for i, s in enumerate(S, 1):
    if s == '(':
        stack.append(('(', i))
    else:
        if stack and stack[-1][0] == '(':
            j = stack[-1][1]
            taiou[i] = j
            taiou[j] = i
            stack.pop()

print(taiou[K])