RT，有无法判断Impossible的问题，但不影响，蒟蒻求调

#include<bits/stdc++.h>
#define endl "\n"
#define mp make_pair
#define int long long
#define ull unsigned long long
using namespace std;
const long long mod=1000000001;
const long long P=201;
map<string,int>a;
int n;
signed main()
{
	cin.tie(0);
	cout.tie(0);
	ios::sync_with_stdio(0);
//	freopen("ce.in","r",stdin);
//	freopen("ce.out","w",stdout);
	string x,y;
	while(cin>>x>>y)
	{
		if(x!=y)++a[x];++a[y];
	}
	int cnt=0;
	for(auto x:a)
	{
		if(x.second%2==1)cnt++;
	}
	if(cnt<=2)cout<<"Possible";
	else cout<<"Impossible";
	return 0;
	exit(0);
}
/*

*/