import java.util.Scanner; public class Kakko{ public static void main(String[] arg){ Scanner sc = new Scanner(System.in); int n,k,res=0,count=0,kc,c,temp=0; String s; n = sc.nextInt(); k = sc.nextInt(); s = sc.next(); int[] m = new int[n]; for(int i = 0;i<n;i++){ if(s.charAt(i) == '('){ count++; m[i] = count; }else{ m[i] = count; count--; } } count = 0; kc = m[k-1]; for(int i = 0;i<n;i++){ if(m[i] == kc){ count++; if(i == k - 1){ c=count; if(c%2 == 0){ res = temp+1; break; }else{ i++; for(;i<n;i++){ if(m[i] == kc){ res = i+1; break; } } break; } } temp = i; } } System.out.println(res); } }