#include <bits/stdc++.h>
using namespace std;

# define REP(i,n) for (int i=0;i<(n);++i)
# define rep(i,a,b) for(int i=a;i<(b);++i)
# define p(s) std::cout << s ;
# define pl(s)  std::cout << s << endl;
# define printIf(j,s1,s2) cout << (j ? s1 : s2) << endl;
# define YES(j) cout << (j ? "YES" : "NO") << endl;
# define Yes(j) std::cout << (j ? "Yes" : "No") << endl;
# define yes(j) std::cout << (j ? "yes" : "no") << endl;
# define all(v) v.begin(),v.end()
# define showVector(v) REP(i,v.size()){p(v[i]);p(" ")} pl("")
template<class T> inline bool chmin(T &a, T b){ if(a > b) { a = b; return true;} return false;}
template<class T> inline bool chmax(T &a, T b){ if(a < b) { a = b; return true;} return false;}
typedef long long int ll;
typedef pair<ll,ll> P_ii;
typedef pair<double,double> P_dd;

template<class T>
vector<T> make_vec(size_t a){
    return vector<T>(a);
}

template<class T, class... Ts>
auto make_vec(size_t a, Ts... ts){
  return vector<decltype(make_vec<T>(ts...))>(a, make_vec<T>(ts...));
}

template<typename T,typename V>
typename enable_if<is_class<T>::value==0>::type
fill_v(T &t,const V &v){t=v;}

template<typename T,typename V>
typename enable_if<is_class<T>::value!=0>::type
fill_v(T &t,const V &v){
  for(auto &e:t) fill_v(e,v);
}


const int MOD = 1000000007;
const int inf=1e9+7;
const ll longinf=1LL<<60 ;

void addM(long long &a, long long b) {
    a += b;
    if (a >= MOD) a -= MOD;
}

void mulM(long long &a, long long b) {
    a = ((a%MOD)*(b%MOD))%MOD ;
}

// a^b mod M
long myPow(long a,long b,int M) {
    long ret = 1;
    long tmp = a;
    while(b>0) {
        if((b&1)==1) ret = (ret * tmp) % M;
        tmp = (tmp * tmp) % M;
        b = b>>1;
    }
    return ret;
}

 // nCk mod M
int nCk(int n,int k,int M) {
    long ret = 1;
    int mi = min(k, n-k);
    for(int i=1;i<=mi;i++) {
        ret = (ret * myPow(i,M-2,M)) % M;
    }
    for(int i=n-mi+1;i<=n;i++) {
        ret = (ret * i) % M;
    }
    return (int)ret;
};

vector<pair<long long, long long> > prime_factorize(long long n) {
    vector<pair<long long, long long> > res;
    for (long long p = 2; p * p <= n; ++p) {
        if (n % p != 0) continue;
        int num = 0;
        while (n % p == 0) { ++num; n /= p; }
        res.push_back(make_pair(p, num));
    }
    if (n != 1) res.push_back(make_pair(n, 1));
    return res;
}

long long int gcd(long long int a,long long int b){
    if(a<b){
        long long int tmp=a;
        a=b;
        b=tmp;
    }

    long long int r = a % b;
    while(r!=0){
        a = b;
        b = r;
        r = a % b;
    }
    return b;
}

long long int lcm(long long int a,long long int b){
    long long int g = gcd(a,b);
    return (a/g)*b;
}


int main() {
    string s;
    cin >> s;

    map<char,int> mp;
    REP(i,s.size()){
        if(mp[s[i]]!=0) {
            pl(-1)
            return 0;
        }
        mp[s[i]]++;
    }

    if(s.size()==26){
        int s_d = 0;
        REP(i,s.size()-1) if(s[i]<s[i+1]) s_d = i+1;
        if(s_d == 0) pl(-1)
        else {
            cout << s.substr(0,s_d-1);
            string sub_s = s.substr(s_d,s.size()-s_d);
            char mi = 'z';
            REP(i,sub_s.size()) if(s[s_d-1] < sub_s[i]) chmin(mi,sub_s[i]);
            cout << mi << endl;            
        }
    } else {
        cout << s;
        REP(i,26){
            char a = (char)'a'+i;
            if(mp[a]==0){
                cout << a << endl;;
                break;
            }
        }
    }

    return 0;
}


Measured memory_bytes: 256