#include<bits/stdc++.h>
using namespace std;
const int N=2e5+5;
int n,m,s,f[N],vis[N];
vector<int>e[N],rs1,rs2;
void slv(int x,vector<int>&rs){
    rs.push_back(x);
    if(x==s)return;
    else slv(f[x],rs);
}
void Fin(){
    puts("Possible");
    printf("%d\n",(int)rs1.size());
    for(int i=(int)rs1.size()-1;~i;i--){
        printf("%d%c",rs1[i],(i)? ' ':'\n');
    }
    printf("%d\n",(int)rs2.size());
    for(int i=(int)rs2.size()-1;~i;i--){
        printf("%d%c",rs2[i],(i)? ' ':'\n');
    }
    exit(0);
}
void dfs(int x,int y){
    // printf("___%d %d\n",x,y);
    vis[x]=y;
    for(auto to:e[x]){
        if(to==s)continue;
        else if(vis[to]==y)continue;
        else if(vis[to]){
            // puts("??????");
            rs1.push_back(to);
            slv(x,rs1);
            slv(to,rs2);
            // puts("<<<");
            Fin();
        }else {
            f[to]=x;
            dfs(to,y);
        }
    }
}
int main(){
    scanf("%d %d %d",&n,&m,&s);
    for(int i=1;i<=m;++i){
        int x,y;
        scanf("%d %d",&x,&y);
        e[x].push_back(y);
    }
    for(auto y:e[s]){
        if(vis[y]){
            rs1.push_back(y),rs1.push_back(s);
            slv(y,rs2);
        }
        f[y]=s;
        dfs(y,y);
    }
    puts("Impossible");
}