import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.io.BufferedWriter;
import java.io.Writer;
import java.io.OutputStreamWriter;
import java.util.InputMismatchException;
import java.io.IOException;
import java.io.InputStream;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 */
public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        OutputWriter out = new OutputWriter(outputStream);
        TaskA solver = new TaskA();
        solver.solve(1, in, out);
        out.close();
    }

    static class TaskA {
        public void solve(int testNumber, InputReader in, OutputWriter out) {
            String s = in.next();
            if (s.equals("zyxwvutsrqponmlkjihgfedcba")) {
                out.println(-1);
                return;
            }
            if (s.length() < 26) {
                boolean[] used = new boolean[26];
                for (char c : s.toCharArray()) used[c - 'a'] = true;
                int w = 0;
                while (used[w]) w++;
                out.println(s + (char) (w + 'a'));
            } else {
                int[] c = new int[s.length()];
                for (int i = 0; i < c.length; i++) c[i] = s.charAt(i) - 'a';
                Permutations.nextPermutation(c);
                String t = "";

                for (int i = 0; i < c.length; i++) {
                    t += (char) (c[i] + 'a');
                    if (c[i] != s.charAt(i) - 'a') break;
                }
                out.println(t);
            }
        }

    }

    static class Permutations {
        public static boolean nextPermutation(int[] p) {
            for (int a = p.length - 2; a >= 0; --a)
                if (p[a] < p[a + 1])
                    for (int b = p.length - 1; ; --b)
                        if (p[b] > p[a]) {
                            int t = p[a];
                            p[a] = p[b];
                            p[b] = t;
                            for (++a, b = p.length - 1; a < b; ++a, --b) {
                                t = p[a];
                                p[a] = p[b];
                                p[b] = t;
                            }
                            return true;
                        }
            return false;
        }

    }

    static class InputReader {
        private InputStream stream;
        private byte[] buf = new byte[1 << 16];
        private int curChar;
        private int numChars;

        public InputReader(InputStream stream) {
            this.stream = stream;
        }

        public int read() {
            if (this.numChars == -1) {
                throw new InputMismatchException();
            } else {
                if (this.curChar >= this.numChars) {
                    this.curChar = 0;

                    try {
                        this.numChars = this.stream.read(this.buf);
                    } catch (IOException var2) {
                        throw new InputMismatchException();
                    }

                    if (this.numChars <= 0) {
                        return -1;
                    }
                }

                return this.buf[this.curChar++];
            }
        }

        public String next() {
            int c;
            while (isSpaceChar(c = this.read())) {
                ;
            }

            StringBuilder result = new StringBuilder();
            result.appendCodePoint(c);

            while (!isSpaceChar(c = this.read())) {
                result.appendCodePoint(c);
            }

            return result.toString();
        }

        public static boolean isSpaceChar(int c) {
            return c == 32 || c == 10 || c == 13 || c == 9 || c == -1;
        }

    }

    static class OutputWriter {
        private final PrintWriter writer;

        public OutputWriter(OutputStream outputStream) {
            writer = new PrintWriter(new BufferedWriter(new OutputStreamWriter(outputStream)));
        }

        public OutputWriter(Writer writer) {
            this.writer = new PrintWriter(writer);
        }

        public void print(Object... objects) {
            for (int i = 0; i < objects.length; i++) {
                if (i != 0) {
                    writer.print(' ');
                }
                writer.print(objects[i]);
            }
        }

        public void println(Object... objects) {
            print(objects);
            writer.println();
        }

        public void close() {
            writer.close();
        }

        public void println(int i) {
            writer.println(i);
        }

    }
}



Measured memory_bytes: 23380