ABBA

#include<cstdio>
#include<sstream>
#include<cstdlib>
#include<cctype>
#include<cmath>
#include<algorithm>
#include<set>
#include<queue>
#include<stack>
#include<list>
#include<iostream>
#include<fstream>
#include<numeric>
#include<string>
#include<vector>
#include<cstring>
#include<map>
#include<iterator>
#include <iomanip>

using namespace std;

// #include <ext/pb_ds/assoc_container.hpp>
// #include <ext/pb_ds/tree_policy.hpp>
// using namespace __gnu_pbds;
// typedef tree<int,null_type,less<int>,rb_tree_tag, tree_order_statistics_node_update> ordered_set;


int main()
{
    string s, t;

    cin>>s>>t;


    while(t.size()>s.size())
    {
        if(t[t.size()-1]=='B')
        {
            t=t.substr(0,t.size()-1);
            reverse(t.begin(),t.end());
        }
        else t=t.substr(0,t.size()-1);

    }

    if(s==t) cout<<"Possible"<<endl;
    else cout<<"Impossible"<<endl;
}