/**
 * code generated by JHelper
 * More info: https://github.com/AlexeyDmitriev/JHelper
 * @author Gosu_Hiroo
 */

#include <iostream>
#include <fstream>

#include <bits/stdc++.h>

using namespace std;
using ll = long long;

#define TR(container, it) \
        for (auto it = container.begin(); it != container.end(); it++)
#define IN(c, x) ((c).find(x) != (c).end())   //O(log n)
#define IN_L(c, x) (find((c).begin(),(c).end(),x) != (c).end()) //O(n)
#define PLL pair<ll,ll>
#define PII pair<int,int>
#define VI vector<int>
#define VVI vector<vector<int>>
#define FOR(i, _begin, _end) for (__typeof(_end) end = _end, begin = _begin,  i = (begin) - ((begin) > (end)); i != (end) - ((begin) > (end)); i += 1 - 2 * ((begin) > (end)))
#define REP(i, end) for (__typeof(end) i = 0, _len = (end); i < (_len); i += 1)
#define ALL(x) (x).begin(),(x).end()
#define SZ(x) ((int)(x).size())
#define F first
#define S second
#define y0 y3487465
#define y1 y8687969
#define j0 j1347829
#define j1 j234892
#define MOD(x, m) ((((x) % (m)) + (m)) % (m))
#define BIT(n) (1LL<<(n))
#define UNIQUE(v) v.erase( unique(v.begin(), v.end()), v.end() );
#define READ ({int t;cin >> t;t;})
#define EB emplace_back
#define fcout cout << fixed << setprecision(12)
#define fcerr cerr << fixed << setprecision(12)

#ifdef DEBUG
#define DBG(x) cerr << #x << " is " << x << endl;
#define ERR(args...) { string _s = #args; replace(_s.begin(), _s.end(), ',', ' '); stringstream _ss(_s); istream_iterator<string> _it(_ss); err(_it, args,cerr); }
#else
#define DBG(x)
#define ERR(args...)
#endif


const double pi = 2 * acos(.0);
const int inf = 0x3f3f3f3f;
const ll mod = (ll) (1e9) + 7;
//const ll mod = (ll) 998244353 ;
const double eps = 1e-10;

void err(istream_iterator<string> it) {}

template<typename T, typename... Args>
void err(istream_iterator<string> it, T a, Args... args, std::ostream &cerr) {
    cerr << *it << " = " << a << endl;
    err(++it, args...);
}

template<typename A, size_t N, typename T>
void Fill(A (&array)[N], const T &val) {
    std::fill((T *) array, (T *) (array + N), val);
}

template<typename T>
ostream &operator<<(ostream &os, const vector<T> V) {
    for (auto v : V)os << v << " ";
    return os;
}

template<typename T>
ostream &operator<<(ostream &os, const set<T> V) {
    for (auto v : V)os << v << " ";
    return os;
}

template<typename T>
ostream &operator<<(ostream &os, const deque<T> V) {
    for (auto v : V)os << v << " ";
    return os;
}

template<class T>
bool Chmax(T &a, const T &b) {
    if (a < b) {
        a = b;
        return 1;
    }
    return 0;
}

template<class T>
bool Chmin(T &a, const T &b) {
    if (b < a) {
        a = b;
        return 1;
    }
    return 0;
}

//#define int ll

class ADiverseWord {
 public:
  string s;
  vector<char> a;
  char c;

  bool exist(int i) {
      char mi = 30+ 'a';
      if(a.empty())return 0;
      for (auto e : a)
          if (e > s[i]) {
              DBG(e)
              Chmin(mi, e);
              c = mi;
              DBG(mi)
          }
      if (mi != (30 + 'a'))return 1;
      return 0;
  }

  void solve(std::istream &cin, std::ostream &cout, std::ostream &cerr) {
      cin >> s;
      if (SZ(s) < 26) {
          REP(i, 26)if (!IN_L(s, i + 'a')){
                  cout << s << (char) (i + 'a') << endl;
                  return;
          }
      } else {
          FOR(i, SZ(s), 0){
              if (exist(i)) {
                  REP(j, i)cout << s[j];
                  ERR(c)
                  string cc = {c};
                  cout << cc;
                  return;
              }
              a.EB(s[i]);
          }
          cout << -1 << endl;
      }


  };
};


#undef int
int main() {

	ADiverseWord solver;
	std::istream& in(std::cin);
	std::ostream& out(std::cout);
    std::ostringstream err;
	in.tie(0); ios::sync_with_stdio(0);
//	solver.solve(in, out);
    solver.solve(in, out,err);
	return 0;
}


Measured memory_bytes: 256