// see https://github.com/LumaKernel/vimfiles/tree/master/snippets/cp-cpp/temp.snip
/// --- .lumrc Template {{{ ///
// #define DEBUG
// #undef DEBUG
// #define assert(...)
#include <bits/stdc++.h>
using namespace std;

using ll = long long;
using ull = unsigned long long;
using ld = long double;
using P = tuple<ll, ll>;
using P3 = tuple<ll, ll, ll>;
using VI = vector<int>;
using VL = vector<ll>;
using VVI = vector<VI>;
using VVL = vector<VL>;
using VP = vector<P>;
using VS = vector<string>;

#define omajinai ios::sync_with_stdio(false),cin.tie(0)

#define FOR(i,a,b) for(int i=int(a);i<int(b);++i)
#define FORI(i,a,b) for(int i=int(a);i<=int(b);++i)
#define REP(i,n) FOR(i,0,n)
#define REPI(i,n) FORI(i,0,n)
#define RFOR(i,a,b) for(int i=int(b)-1;i>=int(a);--i)
#define RFORI(i,a,b) for(int i=int(b);i>=int(a);--i)
#define RREP(i,n) RFOR(i,0,n)
#define RREPI(i,n) RFORI(i,0,n)

#define ALL(a) begin(a),end(a)
#define UNIQUE(a) (a).erase(unique(ALL(a)),(a).end())
#define PB push_back
#define EACH(i,c) REP(i,(c).size())
#define REACH(i,c) RREP(i,(c).size())
#define EXIST(s,e) ((s).find(e)!=(s).end())
#define SORT(c) sort(ALL(c))

#define BR cout<<"\n";

#ifdef DEBUG
#define dump(...) cerr<<"["<<__LINE__<< "] "<<#__VA_ARGS__<<" = "<<make_tuple(__VA_ARGS__)<<"\n";
#else
#define dump(...)
#endif

#define YES(x) cout<<((x)?"YES":"NO")<<"\n";
#define Yes(x) cout<<((x)?"Yes":"No")<<"\n";
#define yes(x) cout<<((x)?"yes":"no")<<"\n";

int __int_temp; ll __ll_temp; string __string_temp;
#define oini (omajinai, cin>>__int_temp, __int_temp)
#define oinl (omajinai, cin>>__ll_temp, __ll_temp)
#define oins (omajinai, cin>>__string_temp, __string_temp)
#define ini (cin>>__int_temp, __int_temp)
#define inl (cin>>__ll_temp, __ll_temp)
#define ins (cin>>__string_temp, __string_temp)

#define isInside(y,x) (0<=(y)&&(y)<h&&0<=(x)&&(x)<w)

#define fi(x) (get<0>(x))
#define se(x) (get<1>(x))
#define th(x) (get<2>(x))
#define fo(x) (get<3>(x))
#define fif(x) (get<4>(x))

template <typename T> ostream &operator<<(ostream &o, const vector<T> &v) { o << '{'; EACH(i, v) o << v[i] << (i != (int)v.size()-1 ? ", " : ""); o << "}";  return o; }

template<int n, class...T> typename enable_if<(n>=sizeof...(T))>::type _ot(ostream &, tuple<T...> const &){}
template<int n, class...T> typename enable_if<(n< sizeof...(T))>::type _ot(ostream & os, tuple<T...> const & t){ os << (n==0?"":", ") << get<n>(t); _ot<n+1>(os, t); }
template<class...T> ostream & operator<<(ostream & os, tuple<T...> const & t){ _ot<0>(os, t); return os; }

template <typename T> inline void smax(T &a, T b) { a = a > b ? a : b; }
template <typename T> inline void smin(T &a, T b) { a = a < b ? a : b; }

template<typename T> inline int intlog2(T x);
template<> inline int intlog2(int x) { return x == 0 ? 0 : 32 - __builtin_clz(x); }
template<> inline int intlog2(ll x) { return x == 0 ? 0 : 64 - __builtin_clzll(x); }

vector<string> split(const string& s, char delim) {
  std::vector<string> elms;
  size_t offset = 0;
  while (true) {
    size_t next = s.find_first_of(delim, offset);
    if (next == string::npos) {
      elms.push_back(s.substr(offset));
      return elms;
    }
    elms.push_back(s.substr(offset, next - offset));
    offset = next + 1;
  }
}

constexpr double PI = acos(-1);

/// }}}--- ///

constexpr int INF = 1e9+1;
constexpr ll LINF = 1e18+1;
constexpr int MOD = 1e9+7;

int main() {
  string s = ins;
  set<int> st;
  for(int i = 0; i < (int) s.size(); i++) {
    st.emplace(s[i] - 'a');
  }
  if(st.size() == 26) {
    set<int> d;
    RFOR(i, 0, 26){
      FOR(j, s[i] - 'a', 26) {
        if(d.count(j)) {
          string ans;
          REP(k, i + 1) {
            ans += s[k];
          }
          ans[i] = char('a' + j);
          cout << ans << endl;
          return 0;
        }
      }
      d.insert(s[i] - 'a');
    }
    cout << -1 << endl;
  } else {
    REP(i, 26) {
      if(!st.count(i)) {
        cout << (s + char('a' + i)) << endl;
        return 0;
      }
    }
  }
}


Measured memory_bytes: 768