import java.io.*;
import java.util.*;
import java.util.Map.Entry;
import java.util.stream.Collectors;

@SuppressWarnings("unused")
public class Main {
	String fileName = "input.txt";
	final boolean isDebug = false;
	//final boolean isDebug = true;
	FastScanner in = new FastScanner(System.in);
	PrintWriter out = new PrintWriter(System.out);
	final int MOD = (int)1e9+7;
	final long INF = Long.MAX_VALUE / 2;
	//final int INF = Integer.MAX_VALUE / 2;
	
	//System.out.println();はつかわない！！
	void solve() throws Exception{
		int H = in.nextInt(), W = in.nextInt();
		char[][] board = new char[H][W];
		for(int i = 0; i < H; i++) board[i] = in.nextStr().toCharArray();
		
		int[][] numH = new int[H][W];
		for(int j = 0; j < W; j++){
			int sum = 0;
			for(int i = 0; i < H; i++){
				if(board[i][j] == '.'){
					sum++;
					numH[i][j] = sum;
				}else{
					if(i != 0) numH[i-1][j] = sum;
					sum = 0;
				}
			}
			int max = 0;
			for(int i = H-1; i >= 0; i--){
				if(numH[i][j] == 0){
					max = 0;
				}else{
					max = Math.max(max, numH[i][j]);
					numH[i][j] = max;
				}
			}
		}
		
		/*
		for(int i = 0; i < H; i++){
			for(int j = 0; j < W; j++){
				out.print(numH[i][j] + " ");
			}
			out.println();
		}
		*/
		
		int[][] numW = new int[H][W];
		for(int i = 0; i < H; i++){
			int sum = 0;
			for(int j = 0; j < W; j++){
				if(board[i][j] == '.'){
					sum++;
					numW[i][j] = sum;
				}else{
					if(j != 0) numW[i][j-1] = sum;
					sum = 0;
				}
			}
			int max = 0;
			for(int j = W-1; j >= 0; j--){
				if(numW[i][j] == 0){
					max = 0;
				}else{
					max = Math.max(max, numW[i][j]);
					numW[i][j] = max;
				}
			}
		}
		
		int ans = 0;
		for(int i = 0; i < H; i++){
			for(int j = 0; j < W; j++){
				ans = Math.max(ans, numH[i][j] + numW[i][j] - 1);
			}
		}
		out.println(ans);
	}
	
	/* end solve */
	
	/* main */
	public static void main(String[] args) throws Exception {
		new Main().m();
	}
	
	void m() throws Exception {
		if(isDebug) in = new FastScanner(new FileInputStream(fileName));
		solve();
		out.flush();
	}
	/* end main */
}
/* end Main */

class FastScanner {
	Reader input;

	FastScanner() {this(System.in);}
	FastScanner(InputStream stream) {this.input = new BufferedReader(new InputStreamReader(stream));}
	
	int nextInt() {return (int) nextLong();}

	long nextLong() {
		try {
			int sign = 1;
			int b = input.read();
			while ((b < '0' || '9' < b) && b != '-' && b != '+') {
				b = input.read();
			}
			if (b == '-') {
				sign = -1;
				b = input.read();
			} else if (b == '+') {
				b = input.read();
			}
			long ret = b - '0';
			while (true) {
				b = input.read();
				if (b < '0' || '9' < b) return ret * sign;
				ret *= 10;
				ret += b - '0';
			}
		} catch (IOException e) {
			e.printStackTrace();
			return -1;
		}
	}

	double nextDouble() {
		try {
			double sign = 1;
			int b = input.read();
			while ((b < '0' || '9' < b) && b != '-' && b != '+') {
				b = input.read();
			}
			if (b == '-') {
				sign = -1;
				b = input.read();
			} else if (b == '+') {
				b = input.read();
			}
			double ret = b - '0';
			while (true) {
				b = input.read();
				if (b < '0' || '9' < b) break;
				ret *= 10;
				ret += b - '0';
			}
			if (b != '.') return sign * ret;
			double div = 1;
			b = input.read();
			while ('0' <= b && b <= '9') {
				ret *= 10;
				ret += b - '0';
				div *= 10;
				b = input.read();
			}
			return sign * ret / div;
		} catch (IOException e) {
			e.printStackTrace();
			return Double.NaN;
		}
	}

	char nextChar() {
		try {
			int b = input.read();
			while (Character.isWhitespace(b)) {
				b = input.read();
			}
			return (char) b;
		} catch (IOException e) {
			e.printStackTrace();
			return 0;
		}
	}

	String nextStr() {
		try {
			StringBuilder sb = new StringBuilder();
			int b = input.read();
			while (Character.isWhitespace(b)) {
				b = input.read();
			}
			while (b != -1 && !Character.isWhitespace(b)) {
				sb.append((char) b);
				b = input.read();
			}
			return sb.toString();
		} catch (IOException e) {
			e.printStackTrace();
			return "";
		}
	}
}

Measured memory_bytes: 98548