n,k = map(int,input().split())
par = [-1]*n
S = list(input())

l = []
for i,s in enumerate(S):
    if s == "(":
        l.append([s,i])
        continue
    if l[-1][0] == "(":
        _,p = l.pop()
        par[p] = i
        par[i] = p
print(par[k-1]+1)