n, k = map(int, input().split())
s = input()
st = []
dic1, dic2 = {}, {}
for i in range(n):
    if i + 1 == k:
        t = s[i]
    if s[i] == "(":
        st.insert(0, i)
    else:
        j = st.pop(0)
        dic1[i] = j
        dic2[j] = i

if t == "(":
    print(dic2[k - 1] + 1)
else:
    print(dic1[k - 1] + 1)