import sys
sys.set_int_max_str_digits(0)

N, K = map(int, input().split())
S = input()
stack = []
for i, s in enumerate(S, 1):
    if stack and stack[-1][0] == '(' and s == ')':
        # stack[-1][1] と i がペア
        x, y = stack[-1][1], i
        if x == K:
            exit(print(y))
        if y == K:
            exit(print(x))
        stack.pop()
    else:
        stack.append((s, i))