#include <iostream>
#include <iomanip>
#include <string>
#include <cmath>
#include <algorithm>
#include <vector>
#include <set>
#include <map>
#include <unordered_map>
#include <unordered_set>
#include <list>
#include <stack>
#include <queue>
#include <bitset>
#include <numeric>
#include <cassert>
#include <array>
#include <memory>
#include <random>
#ifdef DEBUG
#include "./Lib/debug.hpp"
#include "./Lib/Timer.hpp"
#include "./Lib/sample.hpp"
#else
#define dump(...)
#endif

/* (=＾o＾=) */
#define int ll

/* macro */
#define FOR(i, b, e) for(ll i = (ll)(b); i < (ll)(e); ++i)
#define RFOR(i, b, e) for(ll i = (ll)(e-1); i >= (ll)(b); --i)
#define REP(i, n) FOR(i, 0, n)
#define RREP(i, n) RFOR(i, 0, n)
#define REPC(x,c) for(const auto& x:(c))
#define REPI2(it,b,e) for(auto it = (b); it != (e); ++it)
#define REPI(it,c) REPI2(it, (c).begin(), (c).end())
#define RREPI(it,c) REPI2(it, (c).rbegin(), (c).rend())
#define REPI_ERACE2(it, b, e) for(auto it = (b); it != (e);)
#define REPI_ERACE(it, c) REPI_ERACE2(it, (c).begin(), (c).end())
#define ALL(x) (x).begin(),(x).end()
#define cauto const auto&
/* macro func */
template<class T>
inline auto sort(T& t) { std::sort(ALL(t)); }
template<class T>
inline auto rsort(T& t) { std::sort((t).rbegin(), (t).rend()); }
template<class T>
inline auto unique(T& t) { (t).erase(unique((t).begin(), (t).end()), (t).end()); }
template<class T, class S>
inline auto chmax(T& t, const S& s) { if (s > t) { t = s; return true; } return false; }
template<class T, class S>
inline auto chmaxE(T& t, const S& s) { if (s >= t) { t = s; return true; } return false; }
template<class T, class S>
inline auto chmin(T& t, const S& s) { if (s < t) { t = s; return true; } return false; }
inline auto BR() { std::cout << "\n"; }

/* type define */
using ll = long long;
using PAIR = std::pair<ll, ll>;
using VS = std::vector<std::string>;
using VL = std::vector<long long>;
using VVL = std::vector<VL>;
using VVVL = std::vector<VVL>;
using VD = std::vector<double>;
template<class T>
using V = std::vector<T>;

/* using std */
using std::cout;
constexpr char endl = '\n';
using std::cin;
using std::pair;
using std::string;
using std::stack;
using std::queue;
using std::vector;
using std::list;
using std::map;
using std::unordered_map;
using std::multimap;
using std::unordered_multimap;
using std::set;
using std::unordered_set;
using std::unordered_multiset;
using std::multiset;
using std::bitset;
using std::priority_queue;
using std::tuple;

/* constant value */
constexpr ll MOD = 1000000007;
//constexpr ll MOD = 998244353;

/* Initial processing  */
struct Preprocessing { Preprocessing() { std::cin.tie(0); std::ios::sync_with_stdio(0); }; }_Preprocessing;

/* Remove the source of the bug */
inline signed pow(signed, signed) { assert(false); return -1; }

/* define hash */
namespace std {
template <>	class hash<std::pair<ll, ll>> { public:	size_t operator()(const std::pair<ll, ll>& x) const { return hash<ll>()(1000000000 * x.first + x.second); } };
}

/* input */
template<class T> std::istream& operator >> (std::istream& is, vector<T>& vec) { for (T& x : vec) is >> x; return is; }

//=============================================================================================
constexpr ll k = 26;
const string non = string("zyxwvutsrqponmlkjihgfedcba").substr(26 - k, k);
auto solve(const string& s) {

	if (s == non) { return string("-1"); }
	ll n = s.size();
	if (n < k) {
		V<bool> v(k);
		REPC(c, s) { v[c - 'a'] = true; }
		auto ans = s;
		REP(i, k)if (!v[i]) { ans += static_cast<char>(i + 'a'); return ans; }
	} else {
		V<bool> v(k);
		auto mx = s[k - 1];
		RREP(i, k) {
			if (s[i] < mx) {
				auto ans = s.substr(0, i);
				REP(j, k)if (v[j] && j > (s[i] - 'a')) {
					ans += (j + 'a'); break;
				}
				return ans;
			}
			v[s[i] - 'a'] = true;
			chmax(mx, s[i]);
		}
	}
}

auto solve_c(const string& s) {
	if (s == non) { return string("-1"); }
	ll n = s.size();
	if (n < k) {
		V<bool> v(k);
		REPC(c, s) { v[c - 'a'] = true; }
		auto ans = s;
		REP(i, k)if (!v[i]) { ans += static_cast<char>(i + 'a'); return ans; }
	} else {
		auto t = s;
		auto ok = [](const string& s) {
			V<bool> b(k);
			REPC(c, s) if (c >= 'a') {
				if (b[c - 'a']) { return false; }
				b[c - 'a'] = true;
			}
			return true;
		};
		do {
			++t[k - 1];
			RFOR(i, 1, k) {
				if (t[i] <= static_cast<char>(k - 1 + 'a')) { break; }
				if (i == k - 1 || t[i + 1] == ('a' - 1)) { t[i] = ('a' - 1); } else { t[i] = 'a'; }
				++t[i - 1];
			}
		} while (!ok(t));
		string ans = "";
		REPC(c, t)if (c >= 'a') { ans += c; }
		return ans;
	}
}
signed main() {
	/**/
	string s;
	cin >> s;

	auto ans = solve(s);
	cout << ans << endl;

	//auto ans_c = solve_c(s);
	//cout << ans_c << endl;
	/*/
	string s = "abcdefghijklmnopqrstuvwxyz";
	s = s.substr(0, k);
	std::random_device seed;
	ll p = 10;
	std::mt19937_64 mt(((p > 0) ? p : seed()));
	REP(_, 100) {
		std::shuffle(ALL(s), mt);
		auto ans = solve(s);
		auto ans_c = solve_c(s);
		if (ans != ans_c) {
			cout << s << endl;
			dump(ans, ans_c);
			return 0;
		}
	}
	/**/
}

Measured memory_bytes: 384