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

typedef long long ll;
typedef unsigned long long ull;
typedef vector<int> vi;
#define FOR(i,a,b) for(int i=(a);i<(int)(b);i++)
#define rep(i,n) FOR(i,0,n)
#define ALL(x) (x).begin(),(x).end()
#define RALL(x) (x).rbegin(),(x).rend()
#define SZ(x) (int)(x).size()
#define mset(a,x) memset(a,x,sizeof(a))
#define dbg(x) cout<<#x<<": "<<(x)<<"\n"
#define OUT(x) cout<<(x)<<"\n"
#define FASTIO cin.tie(0),ios::sync_with_stdio(0)
#define pb push_back
#define mp make_pair

int main() {
    int n, k;
    string s;
    cin>>n>>k>>s;
    --k;

    int state = 0;
    if(s[k] == '('){
        for(int i = k; i<n; ++i){
            if(s[i] == '(') ++state; else --state;
            if(state == 0){
                OUT(i+1);
                return 0;
            }
        }
    }
    else{
        for(int i = k; i>=0; --i){
            if(s[i] == '(') ++state; else --state;
            if(state == 0){
                OUT(i+1);
                return 0;
            }
        }
    }
    

    return 0;
}