#include <bits/stdc++.h>

using namespace std;

const int MAX_N = 200000 + 5;

int N, M, s;
struct Edge{
    int y, prev;
}e[MAX_N];
int elast[MAX_N], ecnt;
int son[MAX_N], bro[MAX_N], fa[MAX_N], sz[MAX_N], bs[MAX_N], dep[MAX_N], tp[MAX_N], vis[MAX_N], Tm;

void Build(int x, int y) {
    ecnt ++;
    e[ecnt].y = y;
    e[ecnt].prev = elast[x];
    elast[x] = ecnt;
}

void dfs1(int u, int fath) {
    sz[u] = 1;
    vis[u] = Tm;
    fa[u] = fath;
    dep[u] = dep[fath] + 1;
    for (int i = elast[u]; i; i = e[i].prev) {
        int v = e[i].y;
        if (vis[v] != Tm) {
            dfs1(v, u);
            sz[u] += sz[v];
            bro[v] = son[u];
            son[u] = v;
            if (sz[bs[u]] < sz[v]) bs[u] = v;
        }
    }
}

void dfs2(int u, int gr) {
    tp[u] = gr;
    if (bs[u]) dfs2(bs[u], gr);
    for (int v = son[u]; v; v = bro[v]) {
        if (v != bs[u]) dfs2(v, v);
    }
}

int Lca(int u, int v) {
    while (tp[u] != tp[v]) {
        if (dep[tp[u]] < dep[tp[v]]) v = fa[tp[v]];
        else u = fa[tp[u]];
    }
    return dep[u] < dep[v] ? u : v;
}

vector <int> ans1, ans2;
bool dfs3(int u) {
    vis[u] = Tm;
    for (int i = elast[u]; i; i = e[i].prev) {
        int v = e[i].y;
        if (vis[v] != Tm) {
            if (dfs3(v)) return true;
        }else if (v != s) {
            int lca = Lca(u, v);
            if (lca == s) {
                ans1.push_back(v);
                while (u) {
                    ans1.push_back(u);
                    u = fa[u];
                }
                reverse(ans1.begin(), ans1.end());
                while (v) {
                    ans2.push_back(v);
                    v = fa[v];
                }
                reverse(ans2.begin(), ans2.end());
                return true;
            }
        }
    }
    return false;
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0); cout.tie(0);
    
    cin >> N >> M >> s;
    for (int i = 1; i <= M; i ++) {
        int x, y;
        cin >> x >> y;
        Build(x, y);
    }
    Tm = 1;
    dfs1(s, 0);
    dfs2(s, s);
    Tm = 2;
    if (dfs3(s)) {
        cout << "Possible\n";
        cout << ans1.size() << '\n';
        for (auto x : ans1) cout << x << ' ';
        cout << '\n' << ans2.size() << '\n';
        for (auto x : ans2) cout << x << ' ';
        cout << endl;
    }else {
        cout << "Impossible\n";
    }
    
	return 0;
}