#pragma ide diagnostic ignored "misc-no-recursion"

#include "bits/stdc++.h"

using namespace std;
typedef long long ll;
typedef double db;

#define TESTCASE 0

static constexpr int INF = 1e9;

static void solve([[maybe_unused]] int tc) {
    int n,m,s;
    cin >> n >> m >> s;

    vector grafo(n+1,vector<int>());
    for(int i=0;i<m;i++){
        int a,b;
        cin >> a >> b;
        if(b!=s)grafo[a].push_back(b);
    }

    vector<int> vis(n+1,-1),prev(n+1,-1);
    auto dfs = [&](auto dfs, int nodo,int last,int st)->void{
        if(vis[nodo]==st)return;
        if(vis[nodo]!=-1){
            vector<int> sol1,sol2;
            cout<<"Possible\n";
            int pos = nodo;
            while(pos!=s){
                sol1.emplace_back(pos);
                pos = prev[pos];
            }
            sol1.emplace_back(s);
            sol2.emplace_back(nodo);
            pos=last;
            while(pos!=s){
                sol2.emplace_back(pos);
                pos = prev[pos];
            }
            sol2.emplace_back(s);

            reverse(sol2.begin(),sol2.end());
            reverse(sol1.begin(),sol1.end());

            cout<<sol1.size()<<"\n";
            for(auto i : sol1)cout<<i<<" ";
            cout<<"\n";
            cout<<sol2.size()<<"\n";
            for(auto i : sol2)cout<<i<<" ";
            cout<<"\n";
            exit(0);
        }
        vis[nodo]=st;
        prev[nodo]=last;

        for(auto i : grafo[nodo]){
            dfs(dfs,i,nodo,st);
        }
    };

    for(auto i : grafo[s]){
        dfs(dfs,i,s,i);
    }
    cout<<"Impossible\n";
}

int main() {
    ios::sync_with_stdio(false);

    if (const char *f = getenv("REDIRECT_STDOUT"); f) {
        freopen(f, "w", stdout);
    }

    int T = 1;
#if TESTCASE
    cin >> T;
#endif

    for (int t = 1; t <= T; t++) {
        solve(t);
    }

    return 0;
}