/* -*- coding: utf-8 -*-
 *
 * 3453.cc:  No.3453 Crape Shop - yukicoder
 */

#include<cstdio>
#include<algorithm>

using namespace std;

/* main */

int main() {
  int n, a, b;
  scanf("%d%d%d", &n, &a, &b);

  for (int i = 0; i < n; i++) {
    int p;
    scanf("%d", &p);

    a -= (p & 1);
    b -= (p >> 1);
    if (a < 0 || b < 0) { printf("%d\n", i + 1); return 0; }
  }

  puts("-1");
  return 0;
}