#include <bits/stdc++.h>
using namespace std;
const double pi = acos(-1.0);
const double eps = 1e-5;
const int oo = 0x3f3f3f3f;
template <class T>
inline void checkmin(T &a, T b) {
  if (b < a) a = b;
}
template <class T>
inline void checkmax(T &a, T b) {
  if (b > a) a = b;
}
template <class T>
inline T sqr(T x) {
  return x * x;
}
template <class T>
inline T lowbit(T n) {
  return (n ^ (n - 1)) & n;
}
template <class T>
inline int countbit(T n) {
  return (n == 0) ? 0 : (1 + countbit(n & (n - 1)));
}
template <class T>
inline T gcd(T a, T b) {
  T c;
  while (a != 0) {
    c = a;
    a = b % a;
    b = c;
  }
  return b;
}
template <class T>
inline T mabs(T a) {
  if (a < 0)
    return -a;
  else
    return a;
}
typedef vector<int> VI;
typedef vector<VI> VII;
typedef vector<string> VS;
#pragma comment(linker, "/STACK:36777216")
const int N = 5111;
const int MOD = (int)1e9 + 7;
inline int solve(int testnum) {
  int n, a, b;
  scanf("%d%d%d", &n, &a, &b);
  int res = 0, c = 0;
  for (int _ = (0); _ < int(n); _++) {
    int sz;
    scanf("%d", &sz);
    if (sz == 1) {
      if (a > 0)
        --a;
      else if (b > 0) {
        --b;
        ++c;
      } else if (c > 0)
        --c;
      else
        ++res;
    } else if (sz == 2) {
      if (b > 0)
        --b;
      else
        res += 2;
    } else
      throw -1;
  }
  printf("%d\n", res);
  return 0;
}
int main(int argc, char *argv[]) {
  ios::sync_with_stdio(false);
  int t = 1;
  if (argc > 1) t = atoi(argv[1]);
  for (int _t = (1); _t < int(t + 1); _t++) {
    int ret = ::solve(_t);
    if (ret == -1) {
      cerr << "Failed test #" << _t << endl;
      break;
    }
    cerr << "Solved test #" << _t << endl;
  }
  return 0;
}
