1 #include <iostream>
 2 #include<cstdio>
 3 #include<cstring>
 4 #include<cstdlib>
 5 #include<stack>
 6 #include<queue>
 7 #include<iomanip>
 8 #include<cmath>
 9 #include<map>
10 #include<vector>
11 #include<algorithm>
12 #define N 500010
13 using namespace std;
14
15 int degree[N],bin[N],id = 1;
16
17 struct tree
18 {
19     int flag,id;
20     struct tree* next[26];
21 }*root;
22 struct tree* creat()
23 {
24     struct tree *p=(struct tree*)malloc(sizeof(struct tree));
25     p->flag =0;
26     for(int i = 0; i < 26; i++)
27         p->next[i] = NULL;
28     return p;
29 }
30
31 int find(int x)
32 {
33     if(bin[x] != x)
34         bin[x] = find(bin[x]);
35     return bin[x];
36 }
37
38 int hash(char s[])
39 {
40     struct tree *p = root;
41     for(int i = 0; s[i]; i++)
42     {
43         if(p->next[s[i]-'a'] == NULL)
44             p->next[s[i]-'a'] = creat();
45         p = p->next[s[i]-'a'];
46     }
47     if(p->flag != 1)
48     {
49         p->flag = 1;
50         p->id = id++;
51     }
52     return p->id;
53 }
54
55 int check()
56 {
57     int sum = 0;
58     int x = find(1);
59     for(int i = 2; i < id; i++)
60         if(find(i) != x)
61             return 0;
62     for(int i = 1; i < id; i++)
63     {
64         if(degree[i]%2)
65             sum++;
66     }
67     if(sum == 0 || sum == 2)
68         return 1;
69     return 0;
70 }
71
72 int main()
73 {
74     int u,v,x,y;
75     char s1[15],s2[15];
76     memset(degree,0,sizeof(degree));
77     for(int i=1; i<=500000; i++)
78     bin[i]=i;
79     root=creat();
80     while(scanf("%s %s",s1,s2)!=EOF)
81     {
82         u =hash(s1);  v =hash(s2);
83         degree[u]++;   degree[v]++;
84         x=find(u);
85         y=find(v);
86         if(x!=y)
87             bin[x]=y;
88     }
89     if(check()) printf("Possible\n");
90     else printf("Impossible\n");
91     return 0;
92 }