#include <iostream>
#include <cstdio>
#include <algorithm>
#include <map>
#include <cstring>
using namespace std;
typedef unsigned long long ULL;
const int N = 250010 << 1;
int p[N];
int d[N];

ULL getHash(string s) {
    int P = 131, b = 1;
    ULL hash = 0;
    for (int i = 0; i < s.size(); i++) {
        hash = hash + s[i] * b;
        b = b * P;
    }
    return hash;
}

int find(int x) {
    if (x == p[x]) return x;
    return p[x] = find(p[x]);
}

char str1[15], str2[15];
int b[N];

int main() {
#ifndef ONLINE_JUDGE
    freopen("POJ2513.in", "r", stdin);
#endif

    for (int i = 0; i < N; i++) p[i] = i;

    int n = 0, flag = 1;

    while (~scanf("%s%s", str1, str2)) {
        int s1 = getHash(str1) % N, s2 = getHash(str2) % N;
        if (!b[s1]) b[s1] = ++n;
        if (!b[s2]) b[s2] = ++n;
        int x = b[s1], y = b[s2];
        d[x]++, d[y]++;

        if (find(x) != find(y)) p[find(x)] = find(y);
    }

    int odd = 0, cnt = 0;
    for (int i = 1; i <= n; i++) {
        if (p[i] == i) cnt++;
        if (d[i] % 2) odd++;
    }

    if ((odd != 0 && odd != 2) || cnt != 1) flag = 0;

    if (n == 0) flag = 1;

    if (flag)
        puts("Possible");
    else
        puts("Impossible");
    return 0;
}