#include<bits/stdc++.h>
using namespace std;

typedef long long int           ll;
typedef unsigned long long int  ull;
typedef vector<int>             vi;
typedef vector<ll>              vll;
typedef vector<vi>              vvi;
typedef pair<int,int>           pii;
typedef vector< pii >           vpii;
typedef set<int>                sti;

#define pb                      push_back
#define pob                     pop_back
#define mp                      make_pair
#define ff                      first
#define ss                      second
#define loop1(i,n)              for(int i=1; i<=int(n); i++)
#define loop(i,y)               for(int i=0; i<int(y); i++)
#define rloop(i,y)              for(int i=int(y); i>0; i--)
#define rloop1(i,y)             for(int i=int(y)-1; i>=0; i--)
#define read()                  freopen("input.txt", "r", stdin)
#define write()                 freopen("output.txt", "w", stdout)
#define cspf(i)                 printf("Case %d: ", i)
#define all(v)                  v.begin(),v.end()
/// Constants
#define eps                     1e-9
#define PI                      acos(-1.0)  // 3.1415926535897932

int main()
{
    int n,z;
    cin>>n;
    int a[n+1],x[n+1],flg[n+1];
    loop(i,n){
        a[i]=0;
        flg[i]=0;
    }
    z=0;
    loop(i,n){
        cin>>x[i];
        a[x[i]]++;
        if(flg[x[i]]==0){
            z++;
            flg[x[i]]=z;
        }
    }
    loop(i,n){
        if(a[x[i]]==n ){
            if(x[i]==n-1){
                cout<<"Possible"<<endl;
                loop1(j,n){
                    cout<<j;
                    if(j<n)
                        cout<<" ";
                }
                cout<<endl;
                return 0;
            }
            else if(x[i]==0){
                cout<<"Possible"<<endl;
                loop1(j,n){
                    cout<<"1";
                    if(j<n)
                        cout<<" ";
                }
                cout<<endl;
                return 0;
            }
            else
                cout<<"Impossible"<<endl;
            return 0;
        }
        z=n-a[x[i]];
        if(z!=x[i]){
            cout<<"Impossible"<<endl;
            return 0;
        }
    }
    cout<<"Possible"<<endl;
    loop(i,n){
        cout<<flg[x[i]];
        if(i+1<n)
            cout<<" ";
    }
    cout<<endl;
    return 0;
}