#fileencoding: utf-8
from __future__ import print_function

def main():
    paren_left = []
    index = 0
    N, K = [int(i) for i in raw_input().strip().split(" ")]
    S = raw_input().strip()
    target = S[K-1]

    for i, v in enumerate(S):
        if v == "(":
            paren_left.append(i)
        else:
            index = paren_left.pop()

        if target == ")" and i == (K-1):
            print(index+1)
            break
        elif target == "(" and index == (K-1):
            print(i+1)
            break


if __name__ == "__main__":
    main()