#include <bits/stdc++.h>
#define REP(i,n) for(int i=0; i<(n); i++)
using namespace std;
struct cww{cww(){ios::sync_with_stdio(false);cin.tie(0);}}star;
int main()
{
    int N, K;
    string S;
    cin >> N >> K >> S;
    
    stack<int> st;
    vector<int> res( N );
    
    REP( i, N )
    {
        if( S[i] == '(' )
        {
            st.emplace( i );
            continue;
        }
        int tmp = st.top();
        st.pop();
        res[i] = tmp;//left'(' のindex
        res[tmp] = i;//right')'のindex
    }
    cout << res[ K - 1 ] + 1 << endl;
    return 0;
}