/**POJ 2513 Colored Sticks*参考： http://poj.org/showmessage?message_id=181500*Hash + 并查集 + 欧拉通路判定*把每根棍子看成一条无向边*Hash函数来自上面的链接，数据弱所以table 1000 就够了*/#include <cstdio>#include <cstring>const int MAXN = 1000;int parent[MAXN], degree[MAXN];int hash(char *s){	int key = 1;	int len = strlen(s);	for (int i = 0; i < len; i++) {		key = (key * 29 + s[i] - ‘a‘) % MAXN;	}	return key;}void init(){	for (int i = 0; i < MAXN; i++) {		parent[i] = i;		degree[i] = 0;	}}int find(int x){	return parent[x] == x ? parent[x] : parent[x] = find(parent[x]);}void unin(int u, int v){	parent[find(v)] = find(u);}// int find(int x)// {//  int tmp = 0;//  int root = x;//  while (parent[root] >= 0) {//      root = parent[root];//  }//  while (x != root) {//      tmp = parent[x];//      parent[x] = root;//      x = tmp;//  }//  return root;// }// void unin(int root1, int root2)// {//  int sum = parent[root1] + parent[root2];//  if (parent[root1] > parent[root2]) {//      parent[root1] = root2;//      parent[root2] = sum;//  } else {//      parent[root2] = root1;//      parent[root1] = sum;//  }// }int main(){	char color1[11], color2[11];	int odd_degree = 0;	init();	while (~scanf("%s%s", color1, color2)) {		int u = hash(color1);		int v = hash(color2);		degree[u] ++;   degree[v]++;		int root1 = find(u);		int root2 = find(v);		if (root1 != root2)			unin(root1, root2);	}	int root = -1;	for (int i = 0; i < MAXN; i++) {		if (degree[i] > 0) {			if (degree[i] % 2) {				odd_degree++;				if (odd_degree > 2) {					printf("Impossible\n");					return 0;				}			}			if (root == -1)				root = find(i);			else if (root != find(i)) {				printf("Impossible\n");				return 0;			}		}	}	printf("Possible\n");	return 0;}