#include <bits/stdc++.h>
using namespace std;
int ts, kk = 1;
template <class T>
inline T _sq(T a) {
  return a * a;
}
template <class T, class X>
inline T _pow(T a, X y) {
  T z = 1;
  for (int i = 1; i <= y; i++) {
    z *= a;
  }
  return z;
}
template <class T>
inline T _gcd(T a, T b) {
  a = abs(a);
  b = abs(b);
  if (!b) return a;
  return _gcd(b, a % b);
}
template <class T>
inline T _lcm(T a, T b) {
  a = abs(a);
  b = abs(b);
  return (a / _gcd(a, b)) * b;
}
template <class T>
inline T _extended(T a, T b, T &x, T &y) {
  a = _abs(a);
  b = _abs(b);
  T g, x1, y1;
  if (!b) {
    x = 1;
    y = 0;
    g = a;
    return g;
  }
  g = _extended(b, a % b, x1, y1);
  x = y1;
  y = x1 - (a / b) * y1;
  return g;
}
template <class T, class X>
inline bool getbit(T a, X i) {
  T t = 1;
  return ((a & (t << i)) > 0);
}
template <class T, class X>
inline T setbit(T a, X i) {
  T t = 1;
  return (a | (t << i));
}
template <class T, class X>
inline T resetbit(T a, X i) {
  T t = 1;
  return (a & (~(t << i)));
}
template <class T, class X>
inline T togglebit(T a, X i) {
  T t = 1;
  return (a ^ (t << i));
}
template <class T, class X, class Y>
inline T _bigmod(T n, X m, Y mod) {
  unsigned long long ret = 1, a = n % mod;
  while (m) {
    if (m & 1) ret = (ret * a) % mod;
    m >>= 1;
    a = (a * a) % mod;
  }
  ret %= mod;
  return (T)ret;
}
template <class T, class Y>
inline T _modinv(T n, Y mod) {
  return _bigmod(n, mod - 2, mod);
}
int a[50], ans[1010];
int main() {
  vector<int> v;
  int tot = 0, x, n, m, mx;
  cin >> n >> m;
  mx = 0;
  for (int i = 1; i <= m; i++) {
    cin >> x;
    a[i] = x;
    if (a[i] > a[mx]) {
      mx = i;
    }
  }
  if (n == 3) {
    if (m >= 3)
      cout << 1 << " " << 2 << " " << 3 << endl;
    else
      puts("-1");
    return 0;
  }
  for (int i = 1; i <= n; i += 2) {
    v.push_back(i);
  }
  for (int i = 2; i <= n; i += 2) {
    v.push_back(i);
  }
  int p = 0;
  for (int i = 1; i <= a[mx]; i++) {
    if (v[p] == n || ans[v[p] - 1] == mx) break;
    ans[v[p]] = mx;
    ++p;
    if (p == v.size()) break;
  }
  for (int i = 1; i <= m; i++) {
    if (i == mx) continue;
    for (int j = 1; j <= a[i]; j++) {
      if (p == v.size()) break;
      if (ans[v[p] - 1] == i || ans[v[p] + 1] == i) break;
      ans[v[p]] = i;
      ++p;
    }
    if (p == v.size()) break;
  }
  if (p != v.size())
    puts("-1");
  else {
    for (int i = 1; i <= n; i++) {
      cout << ans[i] << " ";
    }
  }
  return 0;
}
