#include <bits/stdc++.h>
using namespace std;
const int INF = 1e9;
const long long LINF = 1e18;
inline long long gcd(long long a, long long b) { return b ? gcd(b, a % b) : a; }
inline long long lcm(long long a, long long b) { return a / gcd(a, b) * b; }
template <class S, class T>
ostream& operator<<(ostream& out, const pair<S, T>& o) {
  out << "(" << o.first << "," << o.second << ")";
  return out;
}
template <class T>
ostream& operator<<(ostream& out, const vector<T> V) {
  for (int i = 0; i < V.size(); i++) {
    out << V[i];
    if (i != V.size() - 1) out << " ";
  }
  return out;
}
template <class T>
ostream& operator<<(ostream& out, const vector<vector<T>> Mat) {
  for (int i = 0; i < Mat.size(); i++) {
    if (i != 0) out << endl;
    out << Mat[i];
  }
  return out;
}
template <class S, class T>
ostream& operator<<(ostream& out, const map<S, T> mp) {
  out << "{ ";
  for (auto it = mp.begin(); it != mp.end(); it++) {
    out << it->first << ":" << it->second;
    if (mp.size() - 1 != distance(mp.begin(), it)) out << ", ";
  }
  out << " }";
  return out;
}
template <class Type>
Type solve(Type res = Type()) {
  long long n;
  cin >> n;
  vector<long long> a(n);
  for (auto& in : a) cin >> in;
  vector<vector<int>> G(n + 1);
  for (int i = 0; i < n; i++) G[n - a[i]].push_back(i);
  for (int i = 1; i <= n; i++) {
    if (G[i].size() % i != 0) {
      cout << "Impossible" << endl;
      return res;
    }
  }
  vector<long long> b(n);
  long long cnt = 1;
  for (int i = 1; i <= n; i++) {
    long long now = 0;
    for (int j = 0; j < G[i].size(); j++) {
      b[G[i][j]] = cnt;
      now++;
      if (now == i) {
        now = 0;
        cnt++;
      }
    }
  }
  cout << "Possible" << endl;
  cout << b << endl;
  return res;
}
int main(void) {
  cin.tie(0);
  ios::sync_with_stdio(false);
  solve<long long>(0);
  return 0;
}
