#include <bits/stdc++.h>
using namespace std;
int n, a, b;
int lb, ub;
int main() {
  scanf("%d%d%d ", &n, &a, &b);
  int l = -1;
  int tot = 0;
  for (int i = 0; i < n; ++i) {
    char c;
    scanf("%c", &c);
    if (c == '*') {
      int k = i - l - 1;
      lb += k / 2;
      ub += (k + 1) / 2;
      l = i;
    } else
      tot++;
  }
  int k = n - l - 1;
  lb += k / 2;
  ub += (k + 1) / 2;
  int mx = 0;
  for (int k = lb; k <= ub; ++k) {
    mx = max(mx, min(a, k) + min(b, tot - k));
    mx = max(mx, min(b, k) + min(a, tot - k));
  }
  printf("%d\n", mx);
}
