#include<bits/stdc++.h>
using namespace std;
#define rep(i,a,b) for(int i=a;i<=b;i++)
int b[500000];
int q=0;
int hsh(string str)
{
	int r=1;
	rep(i,0,str.size()-1)r+=str[i];
	return r%500000;
}
int main()
{
	int num=0;
	string str1,str2;
	while(cin>>str1>>str2)
	{
		b[hsh(str1)]=(b[hsh(str1)]+1)%2;
		b[hsh(str2)]=(b[hsh(str2)]+1)%2;
		num++;
	}
	if(num==0)
	{
		cout<<"Possible";
    	return 0;
	}
	rep(i,1,499999)
	{
		q+=b[i];
		if(q>=3)
		{
			cout<<"Impossible";
			return 0;
		}
	}
	cout<<"Possible";
    return 0;
}