n, k = map(int, input().split())
brackets = input()
stack = []

def debug(stack):
    print(stack)

for index, bracket in enumerate(brackets):
    if bracket == '(':
        stack.append(index + 1)
    
    if bracket == ')':
        popNum = stack.pop()
        if index + 1 == k:
            print(popNum)
            break
        elif popNum == k:
            print(index + 1)
            break
    # debug(stack)