import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.NoSuchElementException;

public class Main{
	static FastScanner sc = new FastScanner();
	static PrintWriter out = new PrintWriter(System.out);
	public static void main(String[] args) {
		int H = sc.nextInt();
		int W = sc.nextInt();
		
		char [][] field = new char [H][W];
		for (int i=0; i<H; i++)
			field [i]=sc.next().toCharArray();
		
		
		int [][] L = new int [H+1][W+1];
		int [][] R = new int [H+1][W+1];
		int [][] D = new int [H+1][W+1];
		int [][] U = new int [H+1][W+1];
		
		for (int i=0; i<H; i++){
			if (field[i][0]=='.')
				L[i+1][1]=1;
			
			for (int j=1; j<W; j++){
				
				if (field[i][j]=='.')
					L[i+1][j+1]=L[i+1][j]+1;
				else
					L[i+1][j+1]=0;
			}	
		}
		
		for (int i=0; i<H; i++){
			if (field[i][W-1]=='.')
				R[i+1][W]=1;
			for (int j=W-1; j>0; j--){
				if (field[i][j-1]=='.')
					R[i+1][j]=R[i+1][j+1]+1;
				else
					R[i+1][j]=0;
			}	
		}
		
		for (int j=0; j<W; j++){
			if (field[0][j]=='.')
				U[1][j+1]=1;
			
			for (int i=1; i<H; i++){
				if (field[i][j]=='.')
					U[i+1][j+1]=U[i][j+1]+1;
				else
					U[i+1][j+1]=0;
			}	
		}
		
		for (int j=0; j<W; j++){
			if (field[H-1][j]=='.')
				D[H][j+1]=1;
			
			for (int i=H-1; i>0; i--){
				if (field[i-1][j]=='.')
					D[i][j+1]=D[i+1][j+1]+1;
				else
					D[i][j+1]=0;
			}	
		}
		
		int cnt = -1;
		for (int i=0; i<H; i++){
			for (int j=0; j<W; j++){
				int temp = R[i+1][j+1]+L[i+1][j+1]+U[i+1][j+1]+D[i+1][j+1]-3;
				cnt = Math.max(temp, cnt);
			}
		}
		out.println(cnt);
		out.flush();
	}

	
	
	
		static class FastScanner {
		    private final InputStream in = System.in;
		    private final byte[] buffer = new byte[1024];
		    private int ptr = 0;
		    private int buflen = 0;

		    private boolean hasNextByte() {
		      if (ptr < buflen) {
		        return true;
		      } else {
		        ptr = 0;
		        try {
		          buflen = in.read(buffer);
		        } catch (IOException e) {
		          e.printStackTrace();
		        }
		        if (buflen <= 0) {
		          return false;
		        }
		      }
		      return true;
		    }

		    private int readByte() {
		      if (hasNextByte()) return buffer[ptr++];
		      else return -1;
		    }

		    private static boolean isPrintableChar(int c) {
		      return 33 <= c && c <= 126;
		    }

		    private void skipUnprintable() {
		      while (hasNextByte() && !isPrintableChar(buffer[ptr])) ptr++;
		    }

		    public boolean hasNext() {
		      skipUnprintable();
		      return hasNextByte();
		    }

		    public String next() {
		      if (!hasNext()) throw new NoSuchElementException();
		      StringBuilder sb = new StringBuilder();
		      int b = readByte();
		      while (isPrintableChar(b)) {
		        sb.appendCodePoint(b);
		        b = readByte();
		      }
		      return sb.toString();
		    }

		    public long nextLong() {
		      if (!hasNext()) throw new NoSuchElementException();
		      long n = 0;
		      boolean minus = false;
		      int b = readByte();
		      if (b == '-') {
		        minus = true;
		        b = readByte();
		      }
		      if (b < '0' || '9' < b) {
		        throw new NumberFormatException();
		      }
		      while (true) {
		        if ('0' <= b && b <= '9') {
		          n *= 10;
		          n += b - '0';
		        } else if (b == -1 || !isPrintableChar(b)) {
		          return minus ? -n : n;
		        } else {
		          throw new NumberFormatException();
		        }
		        b = readByte();
		      }
		    }

		    public int nextInt() {
		      return (int) nextLong();
		    }

		    public int[] nextIntArray(int N, boolean oneBased) {
		      if (oneBased) {
		        int[] array = new int[N + 1];
		        for (int i = 1; i <= N; i++) {
		          array[i] = sc.nextInt();
		        }
		        return array;
		      } else {
		        int[] array = new int[N];
		        for (int i = 0; i < N; i++) {
		          array[i] = sc.nextInt();
		        }
		        return array;
		      }
		    }

		    public long[] nextLongArray(int N, boolean oneBased) {
		      if (oneBased) {
		        long[] array = new long[N + 1];
		        for (int i = 1; i <= N; i++) {
		          array[i] = sc.nextLong();
		        }
		        return array;
		      } else {
		        long[] array = new long[N];
		        for (int i = 0; i < N; i++) {
		          array[i] = sc.nextLong();
		        }
		        return array;
		      }
		    }
		  }

		}	 





Measured memory_bytes: 135444