#include <iostream>
#include <algorithm>
#include <cmath>
#include <vector>
#include <complex>
#include <queue>
#include <deque>
#include <set>
#include <map>
#include <unordered_set>
#include <unordered_map>
#include <iomanip>
#include <assert.h>
#include <array>
#include <cstdio>
#include <cstring>
#include <random>
#include <functional>
#include <numeric>
#include <bitset>

using namespace std;

#define REP(i,a,b) for(int i=a;i<(int)b;i++)
#define rep(i,n) REP(i,0,n)
#define all(c) (c).begin(), (c).end()
#define zero(a) memset(a, 0, sizeof a)
#define minus(a) memset(a, -1, sizeof a)
#define minimize(a, x) a = std::min(a, x)
#define maximize(a, x) a = std::max(a, x)

using ll  = long long;
int const inf = 1<<29;

int main() {

  int N, K; cin >> N >> K; K--;
  string S; cin >> S;
  if(S[K] == '(') {
    int c = 0;
    REP(i, K, inf) {
      if(S[i] == '(') c++;
      if(S[i] == ')') c--;
      if(c == 0) { cout << i+1 << endl; exit(0); }
    }
  }
  else {
    int c = 0;
    for(int i=K;; i--) {
      if(S[i] == ')') c++;
      if(S[i] == '(') c--;
        if(c == 0) { cout << i+1 << endl; exit(0); }
    }
  }

  return 0;
}