import java.util.*;
import java.io.*;
import java.lang.*;

public final class Main {

    private final static boolean USE_FILE_IO = false;

    void solve() throws java.lang.Exception {
        int n = ri();
        int m = ri();
        char[][] a = new char[n][];
        for (int i=0; i<n; i++) {
            a[i] = rline().trim().toCharArray();
        }
        int[][] l = new int[n][m], r = new int[n][m], t = new int[n][m], b = new int[n][m];
        for (int i=0; i<n; i++) {
            for (int j=0; j<m; j++) {
                if (a[i][j] == '#') {
                    l[i][j] = 0;
                    t[i][j] = 0;
                } else {
                    if (j==0) l[i][j] = 1;
                    else l[i][j] = l[i][j-1]+1;
                    if (i==0) t[i][j] = 1;
                    else t[i][j] = t[i-1][j]+1;
                }
            }
        }
        int max = 0;
        for (int i=n-1; i>=0; i--) {
            for (int j=m-1; j>=0; j--) {
                if (a[i][j] == '#') {
                    r[i][j] = 0;
                    b[i][j] = 0;
                } else {
                    if (j==m-1) r[i][j] = 1;
                    else r[i][j] = r[i][j+1]+1;
                    if (i==n-1) b[i][j] = 1;
                    else b[i][j] = b[i+1][j]+1;
                    int sum = l[i][j] + r[i][j] + t[i][j] + b[i][j] - 3;
                    if (sum > max) {
                        max = sum;
                    }
                }
            }
        }
        wr(max);
    }

    public static void main(String[] args) throws java.lang.Exception {
        Reader reader = null;
        Writer writer = null;
        try {
            if (USE_FILE_IO) {
                reader = new Reader(new FileInputStream("input.txt"));
                writer = new Writer(new FileOutputStream("output.txt"));
            } else {
                reader = new Reader(System.in);
                writer = new Writer(System.out);
            }            
            new Main(reader, writer).solve();
        } finally {
            if (reader != null)
                reader.close();
            if (writer != null)
                writer.close();
        }
    }

    Reader reader;
    Writer writer;

    Main(Reader reader, Writer writer) {
        this.reader = reader;
        this.writer = writer;
    }

    int ri() throws java.lang.Exception {
        return reader.nextInt();
    }

    int[] ria() throws java.lang.Exception {
        int n = ri();
        int[] a = new int[n];
        for (int i=0; i<n; i++) a[i] = ri();
        return a;
    }

    long rl() throws java.lang.Exception {
        return reader.nextLong();
    }

    long[] rla() throws java.lang.Exception {
        int n = ri();
        long[] a = new long[n];
        for (int i=0; i<n; i++) a[i] = rl();
        return a;
    }

    double rd() throws java.lang.Exception {
        return reader.nextDouble();
    }

    String rs() {
        return reader.nextToken();
    }

    String rline()  throws java.lang.Exception {
        return reader.nextLine();
    }

    void wr(int x)  throws java.lang.Exception {
        writer.write(x);
    }

    void wr(int[] a)  throws java.lang.Exception {
        for (int i=0; i<a.length; i++) {
            if (i!=0) wr(" ");
            wr(a[i]);
        }
        wl();
    }

    void wr(long x)  throws java.lang.Exception {
        writer.write(x);
    }

    void wr(long[] a)  throws java.lang.Exception {
        for (int i=0; i<a.length; i++) {
            if (i!=0) wr(" ");
            wr(a[i]);
        }
        wl();
    }

    void wr(double x)  throws java.lang.Exception {
        writer.write(x);
    }    

    void wr(String s)  throws java.lang.Exception {
        writer.write(s);
    }

    void wl()  throws java.lang.Exception {
        writer.writeLine();
    }

    void wline(String s)  throws java.lang.Exception {
        writer.writeLine(s);
    }

    static class Writer {
        BufferedWriter bw;

        public Writer(OutputStream out) {
            bw = new BufferedWriter(new OutputStreamWriter(out));
        }

        void write(String s) throws java.lang.Exception {
            bw.write(s);
        }

        void write(int x) throws java.lang.Exception {
            write(String.valueOf(x));
        }

        void write(long x) throws java.lang.Exception {
            write(String.valueOf(x));
        }

        void write(double x) throws java.lang.Exception {
            write(String.valueOf(x));
        }

        void write(char c) throws java.lang.Exception {
            bw.write(c);
        }

        void newLine() throws java.lang.Exception {
            bw.newLine();
        }

        void writeLine(String s) throws java.lang.Exception {
            write(s);
            newLine();
        }

        void writeLine(int n) throws java.lang.Exception {
            writeLine(String.valueOf(n));
        }

        void writeLine(long n) throws java.lang.Exception {
            writeLine(String.valueOf(n));
        }
        
        void writeLine() throws java.lang.Exception {
            writeLine("");
        }

        void close() throws java.lang.Exception {
            bw.flush();
            bw.close();
        }
    }

    static class Reader {
        BufferedReader br;
        StringTokenizer st;

        public Reader(InputStream in) {
            br = new BufferedReader(new InputStreamReader(in));
        }

        String nextToken() {
            while (st == null || !st.hasMoreElements()) {
                try {
                    st = new StringTokenizer(br.readLine());
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            return st.nextToken();
        }

        String[] nextTokens(int n) {
            String[] a = new String[n];
            for (int i=0; i<n; i++) {
                a[i] = nextToken();
            }
            return a;
        }

        int nextInt() {
            return Integer.parseInt(nextToken());
        }

        int[] nextInts(int n) {
            int[] a = new int[n];
            for (int i=0; i<n; i++) {
                a[i] = nextInt();
            }
            return a;
        }

        long nextLong() {
            return Long.parseLong(nextToken());
        }

        long[] nextLongs(int n) {
            long[] a = new long[n];
            for (int i=0; i<n; i++) {
                a[i] = nextInt();
            }
            return a;
        }

        double nextDouble() {
            return Double.parseDouble(nextToken());
        }

        String nextLine() {
            String str = "";
            try {
                str = br.readLine();
            } catch (IOException e) {
                e.printStackTrace();
            }
            return str;
        }

        void close() throws java.lang.Exception {
            br.close();
        }
    }
}

Measured memory_bytes: 116764