def main():

  N,S=(int(x) for x in input().split())

  l = input()

  list = []

  for i in l:
      list.append(i)

  for i in range(N):
        
        i = 0

        if list[i] == "(":

            for j in range(N-(i+1)):

                if list[i+j+1] == "(" or list[i+j+1] == "0":

                   continue   

                elif list[i+j+1] == ")":

                    list[i+j+1] = "0"



                    for k in range(i+j+1,-1,-1):

                        if list[k] == "(":
                             
                            m = k 
                            list[k] = "0"
                            break
    
                    if m+1 == S:
                        print(i+j+2)
                        break
                        
                    elif i+j+2 == S:
                        print(m+1)
                        break
                
                    else:
                        break
                        
if __name__ == "__main__":
    main()