let inpt = readLine()!.split(separator: " ").map({Int($0)!})

let target = inpt[1]

let str = readLine()!.map(Character.init)

var stack = [Int]()

var moji = 0
for i in str {
    moji+=1
    if(i=="(") {
        stack.insert(moji, at: 0)
    } else {
        let tmp = stack.removeFirst()
        if(tmp == target) {
            print(moji)
            break
        }
    }
}