import std.algorithm, std.array, std.container, std.range;
import std.numeric, std.math, std.bigint, std.bitmanip, std.random;
import std.string, std.conv, std.stdio, std.typecons;

void main()
{
  auto rd = readln.split.map!(to!int);
  auto n = rd[0], k = rd[1] - 1;
  auto s = readln.chomp;

  auto a = 0;
  if (s[k] == '(') {
    foreach (i; k..n) {
      a += s[i] == '(' ? +1 : -1;
      if (a == 0) {
        writeln(i + 1);
        break;
      }
    }
  } else {
    foreach_reverse (i; 0..k + 1) {
      a += s[i] == ')' ? +1 : -1;
      if (a == 0) {
        writeln(i + 1);
        break;
      }
    }
  }
}