n, k = map(int, input().split())
s = input()

cor = [0] * n
stack = []
for i in range(n):
    if s[i] == ")":
        j = stack.pop()
        cor[j] = i
        cor[i] = j
    else:
        stack.append(i)

ans = cor[k - 1] + 1
print(ans)