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.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.Collections;
import java.util.InputMismatchException;
import java.util.LinkedList;
import java.util.List;
import java.util.Queue;
public class KseniaAndPawns{
	static PrintWriter out;
	static InputReader in;
	static char[][] board;
	
	static int ROW;
	static int COL;
	static int[][] dp;
	static int ROOT;
	public static void main(String[] args) throws Exception {
		in = new InputReader(System.in);
		out = new PrintWriter(System.out);
		
		ROW = in.nextInt();
		COL = in.nextInt();
		board = new char[ROW][COL];
		
		boolean existPoint = false;
		for(int i=0;i<ROW;i++) {
			board[i] = in.nextToken().toCharArray();
			for(int j=0;j<COL;j++) {
				if(board[i][j] != '#')
					existPoint = true;
			}
		}
		
		if(!existPoint) {
			out.println(0);
			out.close();
			return;
		}
		
		if(isCycle()) {
			out.println(-1);
			out.close();
			return;
		}
		
		List<Integer> maxes = new ArrayList<Integer>();
		int[][] dist = new int[ROW][COL];
		for(int r = 0; r < ROW; r++) {
			for(int c = 0; c < COL; c++) {
				if(board[r][c] != '#') {
					int[] move = move(r,c);
					if(board[r+move[0]][c+move[1]] == '#') {
						// found a root!
						Queue<Integer> q = new LinkedList();
						int max = 1;
						dist[r][c] = 1;
						q.add(r*COL+c);
						while(!q.isEmpty()) {
							int node = q.poll();
							int cr = node / COL;
							int cc = node % COL;
							for(int[] dir : moves) {
								int nr = cr + dir[0];
								int nc = cc + dir[1];
								if(board[nr][nc] == '#') continue;
								int[] cmove = move(nr,nc);
								if(nr + cmove[0] == cr && nc + cmove[1] == cc) {
									dist[nr][nc] = dist[cr][cc]+1;
									max = Math.max(dist[nr][nc], max);
									q.add(nr*COL + nc);
								}
							}
						}
						maxes.add(max);
					}
				}
			}	
		}
		Collections.sort(maxes);
		int ans = 2 * maxes.get(maxes.size()-1)- 1;
		if(maxes.size() > 1) {
			ans = Math.max(ans, maxes.get(maxes.size()-1) + maxes.get(maxes.size()-2));
		}
		out.println(ans);
		out.close();
	}
	
	static boolean isCycle() {
		int[][] visited = new int[ROW][COL];
		int time = 1;
		for(int r = 0; r < ROW; r++) {
			for(int c = 0; c < COL; c++) {
				if(visited[r][c] != 0 || board[r][c] == '#') {
					continue;
				}
				int cr = r;
				int cc = c;
				
				while(true) {
					visited[cr][cc] = time;
					int[] move = move(cr,cc);
					cr += move[0];
					cc += move[1];
					if(visited[cr][cc] == time) {
						return true;
					}
					if(board[cr][cc] == '#')
						break;
				}
				time++;
			}	
		}
		return false;
	}
	
	static int[][] moves = {{1,0},{0,1},{-1,0},{0,-1}};
	static int[] move(int r, int c) {
		char ch = board[r][c];
		if(ch == '>')
			return moves[1];
		else if(ch == '<') 
			return moves[3];
		else if(ch == '^')
			return moves[2];
		else if(ch == 'v')
			return moves[0];
		System.out.println("wtf");
		return null;
	}
	
	static class InputReader {
		private InputStream stream;
		private byte[] buf = new byte[1024];
		private int curChar;
		private int numChars;
		private SpaceCharFilter filter;

		public InputReader(InputStream stream) {
			this.stream = stream;
		}
		
		public int read() {
			if (numChars == -1)
				throw new InputMismatchException();
			if (curChar >= numChars) {
				curChar = 0;
				try {
					numChars = stream.read(buf);
				} catch (IOException e) {
					throw new InputMismatchException();
				}
				if (numChars <= 0)
					return -1;
			}
			return buf[curChar++];
		}

		public int nextInt() {
			int c = read();
			while (isSpaceChar(c))
				c = read();
			int sgn = 1;
			if (c == '-') {
				sgn = -1;
				c = read();
			}
			int res = 0;
			do {
				if (c < '0' || c > '9')
					throw new InputMismatchException();
				res *= 10;
				res += c - '0';
				c = read();
			} while (!isSpaceChar(c));
			return res * sgn;
		}

		public long nextLong() {
			int c = read();
			while (isSpaceChar(c))
				c = read();
			int sgn = 1;
			if (c == '-') {
				sgn = -1;
				c = read();
			}
			long res = 0;
			do {
				if (c < '0' || c > '9')
					throw new InputMismatchException();
				res *= 10;
				res += c - '0';
				c = read();
			} while (!isSpaceChar(c));
			return res * sgn;
		}
		

		public String nextToken() {
			int c = read();
			while (isSpaceChar(c))
				c = read();
			StringBuilder res = new StringBuilder();
			do {
				res.appendCodePoint(c);
				c = read();
			} while (!isSpaceChar(c));
			return res.toString();
		}

		public boolean isSpaceChar(int c) {
			if (filter != null)
				return filter.isSpaceChar(c);
			return isWhitespace(c);
		}

		public static boolean isWhitespace(int c) {
			return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
		}

		public interface SpaceCharFilter {
			public boolean isSpaceChar(int ch);
		}
	}
}
