from collections import deque

n,k = map(int,input().split())
s = list(input())
q = deque([])

for i,x in enumerate(s):
    if x == "(":
        q.append(i+1)
    else:
        y = q.pop()
        if i+1 == k:
            print(y)
        elif y == k:
            print(i+1)
            exit()