#include <bits/stdc++.h>
int main() {
  int n, h, m, i, j, k, count = 0;
  scanf("%d %d %d", &n, &m, &h);
  getchar();
  char c[200009];
  for (i = 0; i < n; i++) scanf("%c", &c[i]);
  j = n - 1 - h;
  k = n - 1 - m;
  for (i = n - 1; i >= k; i--) {
    if (i == j && c[i] == '0')
      count++;
    else if (c[i] == '1' && i != j && i != k)
      count++;
  }
  printf("%d", count);
}
