#include <bits/stdc++.h>
using namespace std;

int main()
{
    int n, k;
    cin >> n >> k;
    string s;
    cin >> s;
    char start;
    int proceed = 0;
    int status = 1;
    if (s[k - 1] == '(')
    {
        proceed = 1;
    }
    else
    {
        proceed = -1;
    }
    start = s[k - 1];
    while (true)
    {
        k += proceed;
        if (s[k - 1] == start)
        {
            status++;
        }
        else
        {
            status--;
        }
        if (!status)
        {
            cout << k << endl;
            // system("pause");
            return 0;
        }
    }
}