#include <bits/stdc++.h>
using namespace std;
const int N = 1e5 + 5;
int n;
int seq[N];
vector<int> zli[N];
int res[N];
int main() {
  scanf("%d", &n);
  for (int i = 1; i <= n; ++i) {
    scanf("%d", seq + i);
    seq[i] = n - seq[i];
    zli[seq[i]].push_back(i);
  }
  int rodzaj = 0;
  for (int ile = 1; ile <= n; ++ile) {
    if ((int)(zli[ile]).size() % ile) {
      puts("Impossible");
      exit(0);
    }
    for (int i = 0; i < (int)(zli[ile]).size(); i += ile) {
      rodzaj++;
      for (int j = i; j < i + ile; ++j) {
        res[zli[ile][j]] = rodzaj;
      }
    }
  }
  puts("Possible");
  for (int i = 1; i <= n; ++i) {
    printf("%d ", res[i]);
  }
  puts("");
}
