#include <bits/stdc++.h>
using namespace std;
const int N = 100005;
vector<int> cnt[N];
int res[N];
int main() {
  int n;
  while (cin >> n) {
    for (int i = 1; i < N; i++) cnt[i].clear();
    for (int i = 1; i <= n; i++) {
      int v;
      cin >> v;
      cnt[v].push_back(i);
    }
    bool ok = true;
    for (int i = 1; i < N; i++) {
      if (i > 1 && cnt[i].size() > cnt[i - 1].size()) ok = false;
      for (int j = 0; j < cnt[i].size(); j++) {
        res[cnt[i][j]] = j + 1;
      }
    }
    if (!ok) {
      printf("%d\n", -1);
    } else {
      printf("%d\n", cnt[1].size());
      for (int i = 1; i <= n; i++) printf("%d%c", res[i], i == n ? '\n' : ' ');
    }
  }
  return 0;
}
