/* -*- coding: utf-8 -*-
 *
 * 2525.cc:  No.2525 Great Move - yukicoder
 */

#include<cstdio>
#include<cstring>
#include<algorithm>
 
using namespace std;

/* constant */

const int MAX_N = 200000;

/* typedef */

/* global variables */

char h[MAX_N + 4], s[MAX_N + 4];

/* subroutines */

/* main */

int main() {
  scanf("%s%s", h, s);
  int hn = strlen(h), sn = strlen(s);

  int f = (h[hn - 1] - s[sn - 1]) & 1;
  if (! f) puts("Possible");
  else puts("Impossible");

  return 0;
}