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

// macros
#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define REP(i,n)  FOR(i,0,n)
#define MIN(a,b) (a>b?b:a)
#define MAX(a,b) (a>b?a:b)
#define INT_IN(a) int a; cin >> a
#define STR_IN(s) string s; cin >> s
#define PRINTLN(s) cout << s << endl
#define PRINTDOUBLELN(s) cout << setprecision(12) << (s) << endl;

// util functions
template<class T> inline T sqr(T x) {return x*x;}

inline int toInt(string s) {int v; istringstream sin(s);sin>>v;return v;}
template<class T> inline string toString(T x) {ostringstream sout;sout<<x;return sout.str();}

template <typename T>inline T max(vector<T> v){T max=v[0]; FOR(i, 1, v.size())max=MAX(v[i], max); return max;}
template <typename T>inline T min(vector<T> v){T min=v[0]; FOR(i, 1, v.size())min=MIN(v[i], min); return min;}
template <typename T>inline vector<T> concat(vector<T> a, vector<T> b){vector<T> ab; ab.reserve(a.size()+b.size());ab.insert(ab.end(),a.begin(),a.end());ab.insert(ab.end(),b.begin(),b.end());return ab;}

// types
typedef long long LL;

// consts
const double EPS = 1e-10;
const double PI  = acos(-1.0);

//debug
#define dump(x)  cerr << #x << " = " << (x)
#define debug(x) cerr << #x << " = " << (x) << " (L" << __LINE__ << ")" << " " << __FILE__

int getIndexOfCloseBracket(int index, string s){
    int nLevel = 0;
    FOR(i, 0, index){
        if(s[i] == '(')nLevel++;
        else nLevel--;
    }
    int pairNLevel = nLevel;
    FOR(i, index, s.length()){
        if(s[i] == '(')nLevel++;
        else nLevel--;
        if(nLevel == pairNLevel)return i;
    }
    return -1;
}

int main(){
    INT_IN(N);
    INT_IN(K);
    STR_IN(s);
    int pIdx = K-1;
    if(s[pIdx] == '('){
        PRINTLN(getIndexOfCloseBracket(pIdx, s) + 1);
    }else{
        REP(i, N){
            if(pIdx == getIndexOfCloseBracket(i, s)){
                PRINTLN(i + 1);
                break;
            }
        }
    }

    return 0;
}