Ksenia has a chessboard of size n × m. Each cell of the chessboard contains one of the characters: "<", ">", "^", "v", "#". The cells that contain character "#" are blocked. We know that all chessboard cells that touch the border are blocked.

Ksenia is playing with two pawns on this chessboard. Initially, she puts the pawns on the chessboard. One cell of the chessboard can contain two pawns if and only if the cell is blocked. In other cases two pawns can not stand in one cell. The game begins when Ksenia put pawns on the board. In one move, Ksenia moves each pawn to a side adjacent cell in the direction of arrows painted on the cell on which the corresponding pawn sits (if the pawn sits on "#", it does not move). Assume that Ksenia moves pawns simultaneously (see the second test case). 

Of course, Ksenia plays for points. How can one calculate the points per game? Very simply! Let's count how many movements the first pawn made and how many movements the second pawn made, sum these two numbers — it will be the resulting score of the game. 

Ksenia wonders: what is the maximum number of points she can earn (for that, she should place the pawns optimally well early in the game). Help her and find that number. 

Input

The first line contains two integers, n and m (1 ≤ n, m ≤ 2000) — the sizes of the board. Each of the following n lines contains m characters – the board's description. Each character is one of the characters: "<", ">", "^", "v", "#".

It is guaranteed that the border cells of the table are blocked cells (with character "#").

Output

If Ksenia can get infinitely many points, print -1. Otherwise, print the maximum number of points she can get.

Examples

Input

1 1
#


Output

0


Input

3 4
####
#&gt;^{}#
####


Output

3

Input

3 4
####
#&gt;&lt;#
####


Output

-1

Input

7 5
#####
##v##
##v##
#####
##^{}##
##^{}##
#####


Output

4

Input

7 5
#####
##v##
##v##
##&lt;##
##^{}##
##^{}##
#####

Output

5
import java.io.InputStreamReader;
import java.io.IOException;
import java.util.Arrays;
import java.io.BufferedReader;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.util.StringTokenizer;
import java.io.InputStream;
import java.lang.Thread;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 */
public class Main implements Runnable {
        public static void main(String[] args) {
                Thread th = new Thread(new ThreadGroup("Main"), new Main(), "solve", 200_000_000L);
                th.start();
                try {
                        th.join();
                } catch (InterruptedException e) {
                        e.printStackTrace();
                }
        }

        @Override
        public void run() {
                InputStream inputStream = System.in;
                OutputStream outputStream = System.out;
                FastScanner in = new FastScanner(inputStream);
                PrintWriter out = new PrintWriter(outputStream);
                TaskD solver = new TaskD();
                solver.solve(1, in, out);
                out.close();
        }
}

class TaskD {
        String[] field;
        short[][] color;
        int dp1[][];
        boolean cycle;
        int n, m;
        int res = 0;

        public void solve(int testNumber, FastScanner in, PrintWriter out) {
                n = in.nextInt();
                m = in.nextInt();
                field = new String[n];
                for (int i = 0; i < n; i++)
                        field[i] = in.nextToken();
                color = new short[n][m];
                for (int i = n - 1; i >= 0; i--)
                        for (int j = m - 1; j >= 0; j--)
                                if (color[i][j] == 0)
                                        dfs1((short)i, (short)j);
                if (cycle) {
                        out.println(-1);
                        return;
                }
                for (int i = 0; i < n; i++)
                        Arrays.fill(color[i], (short)0);
                dp1 = new int[n][m];
                for (int i = 0; i < n; i++)
                        for (int j = 0; j < m; j++)
                                if (color[i][j] == 0)
                                        dfs2((short)i, (short)j);
                int max1 = 0;
                int max2 = 0;
                for (int i = 0; i < n; i++)
                        for (int j = 0; j < m; j++) {
                                int cur = dp1[i][j];
                                if (cur > max1) {
                                        max2 = max1;
                                        max1 = cur;
                                } else if (cur > max2) {
                                        max2 = cur;
                                }
                        }
                res = Math.max(res, max1 + max2);
                out.println(res);
        }

        void dfs1(short x, short y) {
                color[x][y] = 1;
                short nx = -1;
                short ny = -1;
                if (field[x].charAt(y) == '^' && GridUtils.isValid(x - 1, y, n, m)) {
                        nx = (short)(x - 1);
                        ny = y;
                }
                if (field[x].charAt(y) == 'v' && GridUtils.isValid(x + 1, y, n, m)) {
                        nx = (short)(x + 1);
                        ny = y;
                }
                if (field[x].charAt(y) == '>' && GridUtils.isValid(x, y + 1, n, m)) {
                        nx = x;
                        ny = (short)(y + 1);
                }
                if (field[x].charAt(y) == '<' && GridUtils.isValid(x, y - 1, n, m)) {
                        nx = x;
                        ny = (short)(y - 1);
                }
                if (GridUtils.isValid(nx, ny, n, m)) {
                        if (color[nx][ny] == 1)
                                cycle = true;
                        else if (color[nx][ny] == 0)
                                dfs1(nx, ny);
                }
                color[x][y] = 2;
        }

        void dfs2(short x, short y) {
                if (color[x][y] == 1)
                        return;
                color[x][y] = 1;
                for (int d = 0; d < 4; d++) {
                        short nx = (short)(x + GridUtils.dx4[d]);
                        short ny = (short)(y + GridUtils.dy4[d]);
                        if (!GridUtils.isValid(nx, ny, n, m))
                                continue;
                        if (!goesHere(nx, ny, x, y))
                                continue;
                        if (color[nx][ny] != 1)
                                dfs2(nx, ny);
                        int d1 = dp1[nx][ny] + 1;
                        if (d1 > dp1[x][y]) {
                                res = Math.max(res, d1 + dp1[x][y]);
                                dp1[x][y] = d1;
                        } else {
                                res = Math.max(res, d1 + dp1[x][y]);
                        }
                }
        }

        boolean goesHere(int x, int y, int wantX, int wantY) {
                if (field[x].charAt(y) == '^')
                        return x == wantX + 1 && y == wantY;
                if (field[x].charAt(y) == 'v')
                        return x == wantX - 1 && y == wantY;
                if (field[x].charAt(y) == '>')
                        return x == wantX && y == wantY - 1;
                return field[x].charAt(y) == '<' && x == wantX && y == wantY + 1;
        }
}

class FastScanner {
        BufferedReader reader;
        StringTokenizer tokenizer;

        public FastScanner(InputStream inputStream)  {
                reader = new BufferedReader(new InputStreamReader(inputStream));
        }

        public String nextToken() {
                while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                        String line;
                        try {
                                line = reader.readLine();
                        } catch (IOException e) {
                                return null;
                        }
                        tokenizer = new StringTokenizer(line);
                }
                return tokenizer.nextToken();
        }

        public int nextInt() {
                return Integer.parseInt(nextToken());
        }

}

class GridUtils {
        public final static short[] dx4 = {0, 0, -1, 1};
        public final static short[] dy4 = {-1, 1, 0, 0};

        public static boolean isValid(int row, int col, int rowCount, int colCount) {
                return 0 <= row && row < rowCount && 0 <= col && col < colCount;
        }
}