#include <iostream>
#include <list>
#include <vector>
#include <string>
#include <stdio.h>
#include <stdint.h>
#include <iomanip>
using namespace std;

using uint = unsigned int;
using ll = long long;

#define CIN( LL , A ) LL A; cin >> A 
#define GETSEGMENT( A , SEPARATOR ) string A; getline( cin , A , SEPARATOR ) 
#define GETLINE( A ) string A; getline( cin , A ) 
#define FOR_LL( VAR , INITIAL , FINAL_PLUS_ONE ) for( ll VAR = INITIAL ; VAR < FINAL_PLUS_ONE ; VAR ++ ) 
#define FOR_ITR( ARRAY , ITR , END ) for( auto ITR = ARRAY .begin() , END = ARRAY .end() ; ITR != END ; ITR ++ ) 
#define RETURN( LL , ANSWER ) const LL answer_for_contest = ( ANSWER ); cout << answer_for_contest << endl; return 0 
#define DOUBLE( DIGITS , ANSWER ) const double answer_for_contest = ( ANSWER ); cout << fixed << setprecision( DIGITS ) << answer_for_contest << endl; return 0 

template <typename T> inline T Distance( const T& a , const ll& b ){ return a < b ? b - a : a - b; }



int main()
{

  CIN( ll , N );
  CIN( ll , K );
  CIN( string , S );
  N++;
  S = " " + S;
  ll num_K = -1;
  ll layer = 0;
  ll init;
  ll d;
  if( S.substr( K , 1 ) == "(" ){
    init = 0;
    d = 1;
  } else {
    init = N;
    d = -1;
  }
  FOR_LL( i , 1 , N ){
    ll j = init + d * i;
    if( num_K == -1 ){
      if( j == K ){
	num_K = layer;
      }
    }
    if( S.substr( j , 1 ) == "(" ){
      layer++;
    } else {
      layer--;
    }
    if( num_K == layer ){
      RETURN( ll , j );
    }
  }
  RETURN( ll , 0 );

}