#if DEBUG
using Microsoft.VisualStudio.TestTools.UnitTesting;
#endif

using System;
using System.Collections.Generic;
using System.Linq;
using System.Numerics;
using System.Text;
using System.Threading.Tasks;

namespace Contest
{
    class Program
    {
        static long mod = 1000000007;

        static void Main(string[] args)
        {
            var scanner = new IO.StreamScanner(Console.OpenStandardInput());
            var h = scanner.Integer();
            var w = scanner.Integer();
            var map = new List<string>();
            for(int i=0; i<h; i++) map.Add(scanner.ScanLine());

            var ans = GetAns(h, w, map);
            IO.Printer.Out.WriteLine(ans);
            IO.Printer.Out.Flush();
        }

        public static int GetAns(int h, int w, List<string> map)
        {
            var left = new int[h, w];
            var right = new int[h, w];
            var top = new int[h, w];
            var bottom = new int[h, w];

            for (int i = 0; i < h; i++)
            {
                // right
                var lastPos = -1;
                for (int j = w - 1; j >= 0; j--)
                {
                    if (map[i][j] == '#') lastPos = j;
                    right[i, j] = lastPos;
                }

                // left
                lastPos = -1;
                for (int j = 0; j < w; j++)
                {
                    if (map[i][j] == '#') lastPos = j;
                    left[i, j] = lastPos;
                }
            }

            for (int j = 0; j < w; j++)
            {
                // top
                var lastPos = -1;
                for (int i = 0; i < h; i++)
                {
                    if (map[i][j] == '#') lastPos = i;
                    top[i, j] = lastPos;
                }

                // bottom
                lastPos = -1;
                for (int i = h - 1; i >= 0; i--)
                {
                    if (map[i][j] == '#') lastPos = i;
                    bottom[i, j] = lastPos;
                }
            }

            var ret = 0;

            for (int i = 0; i < h; i++)
            {
                for (int j = 0; j < w; j++)
                {
                    if (map[i][j] == '#') continue;

                    var wk = 1;

                    // top
                    wk += top[i, j] == -1 ? i : i - top[i, j] - 1;

                    // bottom
                    wk += bottom[i, j] == -1 ? h - i - 1 : bottom[i, j] - i - 1;

                    // left
                    wk += left[i, j] == -1 ? j : j - left[i, j] - 1;

                    // right
                    wk += right[i, j] == -1 ? w - j - 1 : right[i, j] - j - 1;

                    ret = Math.Max(ret, wk);
                }
            }


            return ret;
        }
    }


#if DEBUG

    [TestClass]
    public class Test
    {
        [TestMethod]
        public void Test1()
        {

        }

        public bool IsEq<T> (List<T> l1, List<T> l2)
        {
            if (l1.Count() != l2.Count()) return false;
            for(int i=0; i<l1.Count(); i++)
            {
                if (!l1[i].Equals(l2[i])) return false;
            }
            return true;
        }
    }

#endif
}

namespace IO
{
    using System.IO;
    using System.Text;
    using System.Globalization;

    public class Printer : StreamWriter
    {
        static Printer()
        {
            Out = new Printer(Console.OpenStandardOutput()) { AutoFlush = false };
        }

        public static Printer Out { get; set; }

        public override IFormatProvider FormatProvider
        {
            get { return CultureInfo.InvariantCulture; }
        }

        public Printer(Stream stream)
            : base(stream, new UTF8Encoding(false, true))
        {
        }

        public Printer(Stream stream, Encoding encoding)
            : base(stream, encoding)
        {
        }

        public void Write<T>(string format, T[] source)
        {
            base.Write(format, source.OfType<object>().ToArray());
        }

        public void WriteLine<T>(string format, T[] source)
        {
            base.WriteLine(format, source.OfType<object>().ToArray());
        }
    }

    public class StreamScanner
    {
        public StreamScanner(Stream stream)
        {
            str = stream;
        }

        public readonly Stream str;
        private readonly byte[] buf = new byte[1024];
        private int len, ptr;
        public bool isEof;

        public bool IsEndOfStream
        {
            get { return isEof; }
        }

        private byte read()
        {
            if (isEof) return 0;
            if (ptr < len) return buf[ptr++];
            ptr = 0;
            if ((len = str.Read(buf, 0, 1024)) > 0) return buf[ptr++];
            isEof = true;
            return 0;
        }

        public char Char()
        {
            byte b;
            do b = read(); while ((b < 33 || 126 < b) && !isEof);
            return (char)b;
        }

        public string Scan()
        {
            var sb = new StringBuilder();
            for (var b = Char(); b >= 33 && b <= 126; b = (char)read())
                sb.Append(b);
            return sb.ToString();
        }

        public string ScanLine()
        {
            var sb = new StringBuilder();
            for (var b = Char(); b != '\n'; b = (char)read())
                if (b == 0) break;
                else if (b != '\r') sb.Append(b);
            return sb.ToString();
        }

        public long Long()
        {
            if (isEof) return long.MinValue;
            long ret = 0;
            byte b;
            var ng = false;
            do b = read(); while (b != 0 && b != '-' && (b < '0' || '9' < b));
            if (b == 0) return long.MinValue;
            if (b == '-')
            {
                ng = true;
                b = read();
            }
            for (; ; b = read())
            {
                if (b < '0' || '9' < b)
                    return ng ? -ret : ret;
                ret = ret * 10 + b - '0';
            }
        }

        public int Integer()
        {
            return (isEof) ? int.MinValue : (int)Long();
        }

        public double Double()
        {
            var s = Scan();
            return s != "" ? double.Parse(s, CultureInfo.InvariantCulture) : double.NaN;
        }

        static T[] enumerate<T>(int n, Func<T> f)
        {
            var a = new T[n];
            for (int i = 0; i < n; ++i) a[i] = f();
            return a;
        }

        public char[] Char(int n)
        {
            return enumerate(n, Char);
        }

        public string[] Scan(int n)
        {
            return enumerate(n, Scan);
        }

        public double[] Double(int n)
        {
            return enumerate(n, Double);
        }

        public int[] Integer(int n)
        {
            return enumerate(n, Integer);
        }

        public long[] Long(int n)
        {
            return enumerate(n, Long);
        }
    }
}


Measured memory_bytes: 90312