#include <stdio.h>
#include <algorithm>
#include <deque>
#include <string>
#include <iostream>
using namespace std;
using ll = long long;

void solve();
int main() {
	solve();
#ifdef DBG
	while (true);
#endif
}

//548
void solve() {
	char s[14], c[13] = { 0 };
	int oc = 0, tc = 0;
	scanf("%s", s);
	
	for (int i = 0; i < 13; i++) {
		if ('m' < s[i])
			break;
		c[s[i] - 'a']++;
		if (c[s[i] - 'a'] == 1)
			oc++;
		else if (c[s[i] - 'a'] == 2)
			oc--, tc++;
		else
			tc--;
	}

	if (oc == 13) {
		for (int i = 0; i < 13; i++)
			printf("%c\n", 'a' + i);
	} else if (tc == 1 && oc == 11) {
		for (int i = 0; i < 13; i++)
			if (c[i] == 0)
				printf("%c\n", 'a' + i);
	} else {
		printf("Impossible\n");
	}
}