#include <iostream>
#define REP(i, a, b) for (int i = a; i < b; i++)
#define REP2(i, a, b) for (int i = a; i <= b; i++)
using namespace std;

int main ()
{
  int N, K;
  cin >> N >> K;
  char str[10000+1];

  REP2 (i, 1, N) cin >> str[i];

  int cnt = 0;
  int n = K;
  for (;;) {
    if (str[n] == '(') {
      cnt++;
    }
    else {  // K番目の括弧が')'の時
      cnt--;
    }
    if (cnt == 0) {
      cout << n << endl;
      return 0;
    }
    if (n == N) n = 1;
  }
  return 0;
}