#include <bits/stdc++.h>
using namespace std;
template <typename Arg1>
void __f(const char* name, Arg1&& arg1) {
  cerr << name << ": " << arg1 << endl;
}
template <typename Arg1, typename... Args>
void __f(const char* names, Arg1&& arg1, Args&&... args) {
  const char* comma = strchr(names + 1, ',');
  cerr.write(names, comma - names) << ": " << arg1 << " |";
  __f(comma + 1, args...);
}
const long long maxn = (long long)3e6 + 100;
const long long maxm = (long long)52;
const int LOGN = 22;
const long long INF = 1e9 + 10;
const long long MOD = 998244353;
const double PI = acos(-1.0);
const double EPS = 1e-12;
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  int n;
  while (cin >> n) {
    vector<pair<int, int> > a(n);
    for (int i = (0); i < ((n)); ++i) {
      int x;
      cin >> x;
      a[i] = {n - x, i};
    }
    sort((a).begin(), (a).end());
    int v = 1;
    bool ok = true;
    vector<int> ans(n);
    for (int i = 0; i < n && ok;) {
      int same = a[i].first;
      for (int j = i; j < i + same; ++j) {
        if (j == n) {
          ok = false;
          break;
        }
        if (a[j].first != same) {
          ok = false;
          break;
        }
        ans[a[j].second] = v;
      }
      ++v;
      i += same;
    }
    if (ok) {
      cout << "Possible\n";
      for (int i = (0); i < ((n)); ++i) cout << ans[i] << " ";
      cout << endl;
    } else {
      cout << "Impossible\n";
    }
  }
  return 0;
}
