#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ii = pair<int, int>;
using i3 = pair<int, ii>;
using li = pair<ll, int>;
using lii = pair<ll, ii>;
using pll = pair<ll, ll>;
using vi = vector<int>;
using vl = vector<ll>;
using vii = vector<ii>;
using vli = vector<li>;
using vpll = vector<pll>;
using vi3 = vector<i3>;
using vlii = vector<lii>;
const int N = 2e5 + 5;
const ll INF = 1e17 + 7;
const double eps = 1e-9, PI = acos(-1);
int n, m;
int ans[N];
int pos[N];
int l[N];
void solve(int testCase) {
  scanf("%d %d", &n, &m);
  int last = 1;
  ll sum = 0;
  for (int i = 1; i <= m; i++) {
    scanf("%d", &l[i]);
    if ((last + l[i] - 1) > n) {
      printf("-1\n");
      return;
    }
    sum += 1ll * l[i];
    ans[last] = i;
    pos[i] = last;
    last++;
  }
  if (sum < (ll)n) {
    printf("-1\n");
    return;
  }
  int can = n;
  for (int i = n; i >= 1; i--) {
    if (ans[i] != 0) {
      if (can <= i + l[ans[i]] - 1) break;
      pos[ans[i]] = can - l[ans[i]] + 1;
      can -= l[ans[i]];
    }
  }
  for (int i = 1; i <= m; i++) {
    printf("%d%c", pos[i], i == m ? '\n' : ' ');
  }
}
int main() {
  int t = 1;
  for (int testCase = 1; testCase <= t; testCase++) {
    solve(testCase);
  }
  return 0;
}
