//#include <bits/stdc++.h>
#include <assert.h>
#include <algorithm>
#include <cmath>
#include <cstring>
#include <iostream>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <vector>
#include <iterator>
using namespace std;

typedef signed long long ll;

#define pp(...) (void)printf(__VA_ARGS__)
#define For(x,to) for(x=0;x<(to);x++)
#define For2(x,arr) for(auto& x:arr)
#define For3(x,c) for(__typeof(c.begin()) x=c.begin();x!=c.end();x++)
#define All(a) (a.begin()),(a.end())
#define Zeros(a) memset(a,0,sizeof(a))
#define Minus(a) memset(a,0xff,sizeof(a))

#define PI 3.14159265
#define EPS (1e-10)
#define EPS_eq(a,b) (abs((a)-(b)) < EPS)

#pragma GCC diagnostic ignored "-Wconversion"

//#define int long long

const int INF = 1000*1000;

int dxy[] = {0, 1, 0, -1, 0};

typedef pair<int, int> P;

signed main() {
    int n,k;
    cin>>n>>k;
    string s;
    cin>>s;
    k--;
    stack<pair<char, int> > sp;
    for(int i=0;i<s.size();i++){
        if(sp.empty()){
            sp.push({s[i], i});
        } else if (sp.top().first == '(' && s[i] == ')'){
            auto pci = sp.top();
            if(pci.second == k){
                printf("%d\n", i + 1);
                return 0;
            } else if (i == k){
                printf("%d\n", pci.second + 1);
                return 0;
            }
            sp.pop();
        } else {
            sp.push({s[i], i});
        }
    }
    assert(sp.empty());
    return 0;
}