n, k = map(int, input().split())
s = input()
num = [0]*n
num[0] = 1
for i in range(1,n):
    if s[i] =="(":
        if s[i-1] ==")":
            num[i] = num[i-1]
        else:
            num[i] = num[i-1] + 1
    if s[i] ==")":
        if s[i-1] =="(":
            num[i] = num[i-1]   
        else:
            num[i] = num[i-1] - 1
            
if s[k-1] == "(":
    for i in range(k,n):
        if num[i] == num[k-1]:
            print(i+1)
            exit()
if s[k-1] == ")":
    for i in range(0,k-1)[::-1]:
        if num[i] == num[k-1]:
            print(i+1)
            exit()