#include <bits/stdc++.h>
using namespace std;
const int N = 2e5 + 10, mod = 1e9 + 7;
int ans[N], a[N];
vector<pair<int, int> > v;
int32_t main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  int n, m;
  cin >> n >> m;
  long long sum = 0;
  for (int i = 0; i < m; i++) {
    cin >> a[i];
    sum += a[i];
  }
  if (sum < n) return cout << -1, 0;
  int cur = 0;
  for (int i = 0; i < m; i++) {
    if (n - cur < a[i]) return cout << -1, 0;
    ans[i] = cur;
    sum -= a[i];
    cur++;
    a[i]--;
    while (a[i] && n - cur > sum) cur++, a[i]--;
  }
  for (int i = 0; i < m; i++) cout << ans[i] + 1 << " ";
  return 0;
}
