import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.UncheckedIOException;
import java.nio.charset.Charset;
import java.util.StringTokenizer;
import java.io.Writer;
import java.io.OutputStreamWriter;
import java.io.BufferedReader;
import java.io.InputStream;

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

    static class CPalindromicMatrix {
        public void solve(int testNumber, LightScanner in, LightWriter out) {
            // out.setBoolLabel(LightWriter.BoolLabel.YES_NO_FIRST_UP);
            int h = in.ints(), w = in.ints();
            int[] cnt = new int[26];
            for (int i = 0; i < h; i++) {
                String s = in.string();
                for (int j = 0; j < w; j++) {
                    cnt[s.charAt(j) - 'a']++;
                }
            }
            int c1 = 0, c2 = 0, c4 = 0;
            for (int i = 0; i < 26; i++) {
                while (cnt[i] >= 4) {
                    cnt[i] -= 4;
                    c4++;
                }
                c2 += cnt[i] / 2;
                c1 += cnt[i] % 2;
            }

            {
                int c4r = (h / 2) * (w / 2);
                if (c4 < c4r) {
                    out.noln();
                    return;
                }
                c4 -= c4r;
                c2 += c4 * 2;
            }

            {
                int c2r = 0;
                if (h % 2 == 1) c2r += w / 2;
                if (w % 2 == 1) c2r += h / 2;
                if (c2 < c2r) {
                    out.noln();
                    return;
                }
                c2 -= c2r;
                c1 += c2 * 2;
            }

            out.ans(c1 == (h % 2) * (w % 2)).ln();
        }

    }

    static class LightScanner {
        private BufferedReader reader = null;
        private StringTokenizer tokenizer = null;

        public LightScanner(InputStream in) {
            reader = new BufferedReader(new InputStreamReader(in));
        }

        public String string() {
            if (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new UncheckedIOException(e);
                }
            }
            return tokenizer.nextToken();
        }

        public int ints() {
            return Integer.parseInt(string());
        }

    }

    static class LightWriter implements AutoCloseable {
        private final Writer out;
        private boolean autoflush = false;
        private boolean breaked = true;
        private LightWriter.BoolLabel boolLabel = LightWriter.BoolLabel.YES_NO_FIRST_UP;

        public LightWriter(Writer out) {
            this.out = out;
        }

        public LightWriter(OutputStream out) {
            this(new BufferedWriter(new OutputStreamWriter(out, Charset.defaultCharset())));
        }

        public LightWriter print(char c) {
            try {
                out.write(c);
                breaked = false;
            } catch (IOException ex) {
                throw new UncheckedIOException(ex);
            }
            return this;
        }

        public LightWriter print(String s) {
            try {
                out.write(s, 0, s.length());
                breaked = false;
            } catch (IOException ex) {
                throw new UncheckedIOException(ex);
            }
            return this;
        }

        public LightWriter ans(String s) {
            if (!breaked) {
                print(' ');
            }
            return print(s);
        }

        public LightWriter ans(boolean b) {
            return ans(boolLabel.transfer(b));
        }

        public LightWriter noln() {
            return ans(false).ln();
        }

        public LightWriter ln() {
            print(System.lineSeparator());
            breaked = true;
            if (autoflush) {
                try {
                    out.flush();
                } catch (IOException ex) {
                    throw new UncheckedIOException(ex);
                }
            }
            return this;
        }

        public void close() {
            try {
                out.close();
            } catch (IOException ex) {
                throw new UncheckedIOException(ex);
            }
        }

        public enum BoolLabel {
            YES_NO_FIRST_UP("Yes", "No"),
            YES_NO_ALL_UP("YES", "NO"),
            YES_NO_ALL_DOWN("yes", "no"),
            POSSIBLE_IMPOSSIBLE_FIRST_UP("Possible", "Impossible"),
            POSSIBLE_IMPOSSIBLE_ALL_UP("POSSIBLE", "IMPOSSIBLE"),
            POSSIBLE_IMPOSSIBLE_ALL_DOWN("possible", "impossible"),
            ;
            private final String positive;
            private final String negative;

            BoolLabel(String positive, String negative) {
                this.positive = positive;
                this.negative = negative;
            }

            private String transfer(boolean f) {
                return f ? positive : negative;
            }

        }

    }
}



Measured memory_bytes: 23380