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

s_list = list(s)
len_s = len(s_list)
comb_list = []
checked = 0

res = None
while checked != n:
    close_index = s_list.index(')')
    open_index = None
    for i in range(close_index):
        if s_list[i] == '(':
            open_index = i
            
    if open_index == k - 1:
        res = close_index + 1
        break
    elif close_index == k - 1:
        res = open_index + 1
        break
        
    s_list[close_index] = 'x'
    s_list[open_index] = 'x'
    checked += 2
    
print(res)