#define rep(i,n) for(int i=0;i<(int)(n);i++)
#define ALL(v) v.begin(),v.end()
typedef long long ll;
 
#include<bits/stdc++.h>
using namespace std;

int main(){
  ios::sync_with_stdio(false);
  std::cin.tie(nullptr);
  
  string h,s;
  cin>>h>>s;
  reverse(ALL(h));
  reverse(ALL(s));
  if((h[0]-s[0])%2==0) cout<<"Possible"<<endl;
  else cout<<"Impossible"<<endl;
  
  return 0;
}