#include <bits/stdc++.h>
using intl = long long;
using itnl = long long;//typo用
using uintl = unsigned long long;
using itn = int;//typo用
using ld = long double;
using namespace std;
#define rep(i, n) for(intl i = 0; i < (intl)(n); i++)
#define rrep(i, n) for(intl i = (intl)(n) - 1; i >= 0; i--)
#define repi(i, a, b) for(intl i = (intl)(a); i < (intl)(b); i++)
#define rrepi(i, a, b) for(intl i = (intl)(a) - 1; i >= (intl)(b); i--)
#define all(x) (x).begin(),(x).end()
#define rall(x) (x).rbegin(),(x).rend()
#define m0(x) memset(x,0,sizeof(x))
#define m1(x) memset(x,1,sizeof(x))
#define fill(x,y) memset(x,y,sizeof(x))
#define alength(a) (sizeof(a) / sizeof(a[0]))
#define debug(x) cout << #x << ":" << x << endl
#define rdebug(i,x) rep(i, alength(x))cout << #x << "[" << i << "]:" << x[i] << endl//1次元配列の出力
#define rrdebug(i, j, x) rep(i, alength(x))rep(j, alength(x[i]))cout << #x << "[" << i << "][" << j << "]:" << x[i][j] << endl//二次元配列の出力
#define pb push_back
#define mp make_pair
#define pii pair<intl,intl>
const intl INF = 1e9;
const intl MOD = 1e9+7;
const ld EPS = 1.0e-14;//-9
const ld PI = acos(-1);
void fp(bool f){cout << (f ? "Yes" : "No") << endl;}
void fp(bool f, string s, string t){cout << (f ? s : t) << endl;}
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; }
intl gcd(intl a, intl b){ if(!b)return a; return gcd(b, a % b); }
intl lcm(intl a,intl b){ return a / gcd(a, b) * b; }
intl kai(intl k){//k!を求める関数,
    intl a = 1;
    for(int i = 2; i <= k; i++){
        a *= i;
    }
    return a;
}
intl digit10(intl a){//aを10進数で表したときの桁数を求める関数
    intl b = 0;
    do{
        a /= 10;
        b++;
    }while(a);
    return b;
}


signed main(){
    cout << fixed << setprecision(10);
    string s;
    cin >> s;
    intl len = s.length();
    if(len < 26){
        bool f[26];
        m0(f);
        rep(i,len)f[s[i] - 'a'] = true;
        rep(i,26){
            if(!f[i]){
                s += (char)(i + 'a');
                break;
            }
        }
    }
    else{
        vector<char> v;
        rep(i,len)v.pb(s[i]);
        next_permutation(all(v));
        string t = "";
        rep(i,26){
            t += v[i];
            if(s[i] != v[i])break;
        }
        s = t;
        if(s == "a")s = "-1";
    }
    cout << s << endl;
    return 0;
}

#include <iostream>
#include <utility>
#include <map>
#include <vector>
#include <algorithm>
#include <queue>
#include <math.h>
#include <stack>
#include <set>
#include <deque>
#include <cmath>

using namespace std;
typedef long long ll;
ll mod = 1e9+7;
//ll mod = 998244353;
#define rep(i,n) for(int i = 0; i < (n); ++i)

int main() {
    string s;
    cin >> s;
    int n = s.size();
    if (n != 26) {
        vector<bool> flg(26, false);
        rep(i, n) flg[s[i]-'a'] = true; 
        cout << s;
        rep(i, 26) {
            if (!flg[i]) {
                cout << (char)(i + 'a') << endl;
                return 0;
            }
        }
    }
    else {
        string t = s;
        if (!next_permutation(t.begin(), t.end())) {
            cout << -1 << endl;
            return 0;
        }
        rep(i, n) {
            cout << t[i];
            if (t[i] != s[i]) {
                cout << endl;
                break;
            } 
        }
    }
    return 0;
}
