// #define _CRT_SECURE_NO_WARNINGS
// #define _USE_MATH_DEFINES	// M_PI=3.1415...
#include <iostream>
#include <cstdio>
#include <algorithm>
#include <string>
#include <vector>
#include <map>
#include <set>
#include <stack>
#include <cmath>
#include <cstdlib>
#include <functional>
#include <locale>
#include <cctype>
#include <sstream>
#include <iomanip>	// 20桁出力 cout << setprecision(20) << double;
#include <queue>
#include <bitset>	// bitset<8> bs1(131uL); // 10000011 bs1[0]は1 01stringからビット集合生成可
#include <numeric>
#include <random>
#include <climits>  // A/Bを計算するときA==LLONG_MIN && B==-1のみ(1ull<<63)で代用
using namespace std;

typedef long long LL;
typedef pair<LL, LL> P;
typedef vector<int> VI;
typedef vector<VI> VVI;
typedef vector<LL> VL;
typedef vector<VL> VVL;				// VVL v(100,VL(100,0));
typedef vector<pair<LL, LL> > VP;
typedef vector<string> VS;
typedef map<int, int> MAPII;
typedef multimap<int, char, greater<int> > MuMAPIC;
typedef multimap<int, string, greater<int> > MuMIS;
typedef pair<LL, pair<P, P> > PP;

#define INF 999999999999999997		// 少し加算したらオーバーフローする
#define MP make_pair
#define FAST_IO  cin.tie(0); ios::sync_with_stdio(false);
#define FOR(i,a,b) for(int i=(a);i<(b);i++)
#define FORL(i,a,b) for(LL i=(a);i<(b);i++)
#define FOR_REV(i,a,b) for(int i=(a);i>=(b);i--)
#define foreach_it(type,it,c) for(type::iterator it=c.begin(),c_end=c.end();it!=c_end;++it)
#define FOR_ITR(d) for(auto itr=d.begin(),d_end=d.end();itr!=d_end;++itr)	// C++11
#define O(s) cout<<s<<endl;

#define DUMP_VVI(b) if(dbgF){FOR(i,0,b.size()){FOR(j,0,b[i].size())printf("%d ",b[i][j]);puts("");}}
#define D_OUT(str,value) if(dbgF){cout<<str<<" : "<<value<<endl;}

template<class T>T IN() { T d; cin >> d; return d; }

LL gcd(LL a, LL b) { return (b > 0) ? gcd(b, a%b) : a; } // 最大公約数（Greatest Common Divisor）
LL lcm(LL a, LL b) { return a / gcd(a, b) * b; } // 最小公倍数（Least Common Multiple）
bool uruu(LL Y) { return (((Y % 4 == 0 && Y % 100 != 0) || Y % 400 == 0) ? true : false); } // うるう年判定
string Replace(string S, string from, string to) { auto p = S.find(from); while (p != string::npos) { S.replace(p, from.size(), to); p = S.find(from, p + to.size()); }return S; }

int dx[4] = { 0,1,0,-1 };
int dy[4] = { 1,0,-1,0 };
int dxx[8] = { 0,1,1,1,0,-1,-1,-1 };
int dyy[8] = { 1,1,0,-1,-1,-1,0,1 };

// -------------------------------------------------------------------------------

int main() {
	FAST_IO;
	bool dbgF = true; // for D_OUT(str, value)  ... cout<< str <<" : "<< value <<endl;

	string S;
	cin >> S;
	VI count(26, 0);

	FOR(i, 0, S.length()) {
		count[S[i] - 'a']++;
	}

	if (S == "zyxwvutsrqponmlkjihgfedcba") {
		O(-1);
		return 0;
	}
	else {
		bool f = 1;
		FOR(i, 0, count.size()) {
			if (count[i] == 0)f = 0;
		}
		if (f == 0) {
			FOR(i, 0, count.size()) {
				if (count[i] == 0) {
					char aa = 'a';
					aa += i;
					string ans = S + aa;
					O(ans);
					return 0;
				}
			}
		}
		else {
			// 末尾からインクリ試す
			string srev = S;
			reverse(srev.begin(),srev.end());
			FOR(i, 0, srev.length()) {
				// S[i]を見る
				// count とりなおし
				VI count3(26, 0);
				FOR(j, i+1, srev.length()) {
					//cout << "now=" << srev[j] << endl;
					int temp = srev[j] - 'a';
					count3[temp]++;
				}

				//FOR(i, 0, count3.size()) {
				//	cout << count3[i];
				//}
				//cout << endl;

				// check
				FOR(j, srev[i] - 'a'+1, count3.size()) {
					if (count3[j] == 0) {
						srev[i] = 'a' + j;
						//out
						reverse(srev.begin(), srev.end());
						FOR(k, 0, 26-(i)) {
							cout << srev[k];
						}
						cout << endl;
						return 0;
					}
				}
			}


			//VI count2(26, 0);
			//string ans;
			//FOR(i, 0, S.length()) {
			//	count2[S[i] - 'a']++;
			//	FOR(j, 26-('z' - S[i]), count2.size()) {
			//		if (count2[j] == 0) {
			//			S[i]++;
			//			//out
			//			FOR(k, 0, i + 1) {
			//				cout << S[k];
			//			}
			//			cout << endl;
			//			return 0;
			//		}
			//	}
			//}


			//// zの1個前インクリ
			//FOR(i, 0, S.length()) {
			//	if (S[i] == 'z') {
			//		char now = S[i - 1];
			//		now++;
			//		S[i - 1] = now;
			//		break;
			//	}
			//	else {
			//		cout<<S[i];
			//	}
			//}
			//cout << endl;
		}




		//string srev = S;
		//srev.reserve();
		//FOR(i, 0, srev.length()) {
		//	if(srev[i]!='z')srev[i]++;
		//}
	}
	O(-1);

	return 0;
}

Measured memory_bytes: 256