#include <iostream>
#include <vector>
#include <string>
#include <algorithm>
#include <cmath>
#include <map>
#include <stack>
#include <queue>
#include <cstdlib>
#include <numeric>


/*
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:::::::::' ;!!!!!!!!; ``:::::' ;' ,c$$$$$$$$$$$CC<<"  ````_ ::::::::::::::
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::: ;><!!!!!!!!! ,<!!!!!!!',c,  "??.< . "??h. -;;;;!!!!!!!' ::::::::::::::
::: !!!!!!!!!!' ;!!!!!!!!' d$$h.`$ccr,$h `;,."  `!!!!!!!!! :::::::::::::::
:::.`<!!!!!!!' !!!!!!!!!! dP"""?.`$$F`$$h.`!!!!!!!!!!!!!! .:::::::::::::::
::::. <!!!!!! !!!!!!!!!! ,$ .nn.' "$$ P"   <!!!!!!!!!!!' .::::::::::::::::
:::::. <!!!! ;!!!!!!!!!! $$ MMMMx  ?$  ,dx `!!!!!!!!!!' ::::::::::::::::::
```:::: `!!! !!!'!!!!!!  `$ MMMMMM, $r MMMr !!!!!!!!' .:::::::::::::::::::
`!!;,.`' ``' ``,;!!!!' ch." 4MMMMMM "$ 4MMM `!!!!!' ..::::::::::::::::::::
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MMMMMM,' .?$$$$$$$$$$ d$$$    d$$$$$$$$$$$$$h..``::::::::::::::::'
MMMMMMMn `?$$$$$$$$$$,.?$$h. =."?$$$$$$$$$$$$$$hc,.``'::::::::::'
MMMMMMMM ;, `"??$$$$$$h  ?$$h. -m,``""??$$$$$$$$$$$$$c,.``````'
MMMMMMM> !!! ?cc,.,d$$$$h.`"?$hc   `P  .`"?$$$$$$$$$$$$$$$$$$$          .:
MMMMMMM ,!!'. $$$$$$$$$??=== `"""=c, " P  n. "$$$$$$$$$$$$$$$$c_    ,.::::
MMMMMMP !!! Mr<$$$$"".,c,;M ;<!! ..""=_ ' 4 .br .`""??$$$$$$$$??"".:::::::
MMMMMM';!!',M>'$$$$$$$$$>4M `!!! 4MMbn.`"=cc," -'P",c=.,.`.. .=  :::::::::
MMMMM' !!! dMb $$$$$$$$P MM> !!! 4MMMMMMr :..`"-._""Pr4"'-P" .,.`:::::::::
MMMM' <!!!,MMM "$$$$$$P dMM>;!!! 4MMMMMMb :::::.. "-=cczyycc??" .:::::::::
MMMP <!!! dMMMb "?$$P" uMMM>;!!! 4MMMMMMMr`:::::::::.........:::::::::::::
MMP';!!! ;MMMMMMn,.".uMMMMM ;!!! MMMMMMMMM,`::::::::::::::::::::::::::::::
MM ;!!!! MMMMMMMMMMMMMMMMMM !!!! MMMMMMMMMb `:::::::::::::::::::::::::::::
M" !!!! uMMMMMMMMMMMMMMMMMP !!! ;MMMMMMMMMMx :::::::::::::::::::::::::::::
P.!!!! ,MMMMMMMMMMMMMMMMMM ,!!! MMMMMMMMMMMMx`::::::::::::::::::::::::::::
!!!!> MMMMMMMMMMMMMMMMMMP !!!',MMMMMMMMMMMMM `:::::::::::::::::::::::::::
*/


int main()
{
	std::string s;


	std::cin >> s;

	std::map<char, int> m;

	for (size_t i = 0; i < s.length(); i++) {
		m[s[i]]++;
	}

	std::sort(s.begin(), s.end());

	if (s.back() > 'm') {
		std::cout << "Impossible" << std::endl;
		return 0;
	}

	int doble = 0;
	std::string ans = "abcdefghijklm";
	char c;

	for (size_t i = 0; i < ans.length(); i++) {
		if (m[ans[i]] == 2) {
			doble++;
		} else if (m[ans[i]] > 2) {
			std::cout << "Impossible" << std::endl;
			return 0;
		} else if (m[ans[i]] == 0) {
			c = ans[i];
		}
	}

	if (doble > 1) {
		std::cout << "Impossible" << std::endl;
		return 0;
	} else if (doble == 1) {
		std::cout << c << std::endl;
	} else {
		for (size_t i = 0; i < ans.length(); i++) {
			std::cout << ans[i] << std::endl;
		}
		
	}

	return 0;
}