#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int main(int argc, const char * argv[]) {
  int n, k, c, l = 0;
  char *d;

  scanf("%d %d", &n, &k);
  k--;
  d = (char *)malloc(sizeof(char) * (n + 1));
  scanf("%s", d);

  if(d[k] == '(') {
    c = k;
    do {
      c++;
      if(d[c] == '(')
        l++;
      else
        l--;
    }while(l >= 0);
  }
  else {
    c = k;
    do {
      c--;
      if(d[c] == ')')
        l++;
      else
        l--;
    }while(l >= 0);
  }

  printf("%d\n", c + 1);

  return EXIT_SUCCESS;
}