import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;

public class Main {

    public static void main(String[] args) throws Exception {
        try (Reader r = new Reader(System.in)) {
            int H = r.i();
            int W = r.i();

            boolean[][] G = new boolean[H][W];
            for (int i = 0; i < H; i++) {
                char[] c = r.s().toCharArray();
                for (int j = 0; j < W; j++) {
                    G[i][j] = (c[j] == '.');
                }
            }

            int[][] L = new int[H][W]; // left
            int[][] R = new int[H][W]; // right
            int[][] U = new int[H][W]; // up
            int[][] D = new int[H][W]; // down

            for (int i = 0; i < H; i++) {
                for (int j = 0; j < W; j++) {
                    if (G[i][j]) {
                        L[i][j] = (j == 0) ? 1 : L[i][j - 1] + 1;
                    }
                }

                for (int j = W - 1; j >= 0; j--) {
                    if (G[i][j]) {
                        R[i][j] = (j == W - 1) ? 1 : R[i][j + 1] + 1;
                    }
                }
            }

            for (int j = 0; j < W; j++) {
                for (int i = 0; i < H; i++) {
                    if (G[i][j]) {
                        U[i][j] = (i == 0) ? 1 : U[i - 1][j] + 1;
                    }
                }

                for (int i = H - 1; i >= 0; i--) {
                    if (G[i][j]) {
                        D[i][j] = (i == H - 1) ? 1 : D[i + 1][j] + 1;
                    }
                }
            }

            int max = 0;
            for (int i = 0; i < H; i++) {
                for (int j = 0; j < W; j++) {
                    max = Math.max(max, L[i][j] + R[i][j] + U[i][j] + D[i][j]);
                }
            }

            System.out.println(max - 3);
        }
    }

    public static class Reader implements AutoCloseable {

        private BufferedReader br;

        private String[] buf;

        private int bufidx = -1;

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

        @Override
        public void close() throws Exception {
            br.close();
        }

        private void readBuf() throws IOException {
            if (bufidx == -1 || bufidx == buf.length) {
                buf = br.readLine().split(" ");
                bufidx = 0;
            }
        }

        public String s() throws IOException {
            readBuf();
            return buf[bufidx++];
        }

        public int i() throws IOException {
            return Integer.parseInt(s());
        }

        public long l() throws IOException {
            return Long.parseLong(s());
        }

        public double d() throws IOException {
            return Double.parseDouble(s());
        }

        public String[] sa() throws IOException {
            readBuf();
            if (bufidx != 0) {
                throw new RuntimeException("illegal read");
            }
            bufidx = -1;
            return buf;
        }

        public int[] ia() throws IOException {
            String[] sa = sa();
            int[] ia = new int[sa.length];
            for (int i = 0; i < sa.length; i++) {
                ia[i] = Integer.parseInt(sa[i]);
            }
            return ia;
        }

        public long[] la() throws IOException {
            String[] sa = sa();
            long[] la = new long[sa.length];
            for (int i = 0; i < sa.length; i++) {
                la[i] = Long.parseLong(sa[i]);
            }
            return la;
        }

        public double[] da() throws IOException {
            String[] sa = sa();
            double[] da = new double[sa.length];
            for (int i = 0; i < sa.length; i++) {
                da[i] = Double.parseDouble(sa[i]);
            }
            return da;
        }

        public int[][] im(int N) throws IOException {
            int[][] im = new int[N][];
            for (int i = 0; i < N; i++) {
                im[i] = ia();
            }
            return im;
        }

        public long[][] lm(int N) throws IOException {
            long[][] lm = new long[N][];
            for (int i = 0; i < N; i++) {
                lm[i] = la();
            }
            return lm;
        }

        public double[][] dm(int N) throws IOException {
            double[][] dm = new double[N][];
            for (int i = 0; i < N; i++) {
                dm[i] = da();
            }
            return dm;
        }

    }

}


Measured memory_bytes: 108252