import java.io.*;
import java.util.ArrayDeque;

public class Main {
    static ArrayDeque<Integer> queue = new ArrayDeque<>(1002);
    public static void main(String[] args) throws IOException {
        BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
        BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(System.out));
        String[] temp = reader.readLine().split(" ");
        int n = Integer.parseInt(temp[0]);
        int m = Integer.parseInt(temp[1]);
        int[][] s = new int[n+2][m+2];
        int[] l = new int[m+2], r = new int[m+2];
        //将左右两侧边界初始化为-1,
        for (int i = 0; i <= n; i++) {
            s[i][0] = s[i][m+1] = -1;
        }
        //读入数据
        for (int i = 1; i <= n; i++) {
            temp = reader.readLine().split(" ");
            for (int j = 1; j <= m; j++) {
                s[i][j] = temp[j-1].equals("R") ? 0 : s[i-1][j] + 1;
            }
        }
        long res = 0;
        for (int i = 1; i <= n; i++) {
            res =Math.max(res, work(s[i], l, r, m));
        }
        writer.write(res*3+"");
        writer.flush();
    }
    static long work(int[] h,int[] l,int[] r, int m){
        queue.clear();
        queue.push(0);
        for (int i = 1; i <= m; i++) {
            while(h[i] <= h[queue.peek()]) queue.pop();
            l[i] = queue.peek();
            queue.push(i);
        }
        queue.clear();
        queue.push(m+1);
        for (int i = m; i > 0; i--) {
            while(h[i] <= h[queue.peek()]) queue.pop();
            r[i] = queue.peek();
            queue.push(i);
        }
        long res = 0;
        for (int i = 1; i <= m; i++) {
            res = Math.max(res, (long)h[i]*(r[i]-l[i]-1));
        }
        return res;
    }
}