#include <bits/stdc++.h>

using namespace std;

#define FOR(i, a, b) for(int i = (a); i < (b); i++)
#define RFOR(i, a, b) for(int i = (a) - 1; i >= (b); i--)
#define SZ(a) int(a.size())
#define ALL(a) a.begin(), a.end()
#define PB push_back
#define MP make_pair
#define F first
#define S second

typedef long long LL;
typedef vector<int> VI;
typedef pair<int, int> PII;
typedef double db;

const int N = 507;
string grid[N];

int n, m;
bool ok(int i, int j)
{
	return 0 <= i && i < n && 0 <= j && j < m;
}

string moves = "<v>^";
PII d[4] = {MP(0, -1), MP(1, 0), MP(0, 1), MP(-1, 0)};

PII to[N][N];
vector<PII> from[N][N];
bool used[N][N];

int was[N][N];
int cnt = 0;
int ans = 0;

void add(int i, int j)
{
	FOR(k, 0, 4)
	{
		int ni = i + d[k].F;
		int nj = j + d[k].S;
		
		if(ok(ni, nj) && grid[ni][nj] == '#')
		{
			if(was[ni][nj] == 0)
				cnt++;
			was[ni][nj]++;
		}
	}
	ans = max(ans, cnt);
}
void remove(int i, int j)
{
	FOR(k, 0, 4)
	{
		int ni = i + d[k].F;
		int nj = j + d[k].S;
		
		if(ok(ni, nj) && grid[ni][nj] == '#')
		{
			was[ni][nj]--;
			if(was[ni][nj] == 0)
					cnt--;				
		}
	}
}


void dfs(PII v)
{
	add(v.F, v.S);
	used[v.F][v.S] = 1;
	for(auto u : from[v.F][v.S])
	{
		if(!used[u.F][u.S])
			dfs(u);
	}
	remove(v.F, v.S);
}

	
int main()
{
	ios::sync_with_stdio(0);
	cin.tie(0);
	
	cin >> n >> m;
	FOR(i, 0, n)
	{
		cin >> grid[i];
		
		FOR(j, 0, m)
		{
			to[i][j] = {-1, -1};
			if(grid[i][j] == '.' || grid[i][j] == '#')
			{
				used[i][j] = 1;
			}
			else
				used[i][j] = 0;
		}
	}
	FOR(i, 0, n)
	{
		FOR(j, 0, m)
		{
			if(used[i][j])
				continue;
				
			FOR(k, 0, 4)
			{
				//cerr << grid[i][j] << " " << moves[k] << "\n";
				if(grid[i][j] != moves[k])
					continue;
				
				int ni = i + d[k].F;
				int nj = j + d[k].S;
				//cerr << i << " " << j << " " << ni << " " << nj << "\n";
					
				if(ok(ni, nj) && !used[ni][nj])
				{
					to[i][j] = {ni, nj};
				//	cerr << i << " " << j << " " << ni << " " << nj << "\n";
					from[ni][nj].PB({i, j});
				}
			}
		}
	}
	
	FOR(i, 0, n)
	{
		FOR(j, 0, m)
		{
			if(used[i][j])
				continue;
			PII v = {i, j};
			vector<PII> st;
			
			while(v.F != -1 && !used[v.F][v.S])
			{
				st.PB(v);
				used[v.F][v.S] = 1;
				v = to[v.F][v.S];
			}
			for(auto u : st)
				used[u.F][u.S] = 0;
			
			vector<PII> cyc;
				
			if(v.F == -1)
			{
				cyc.PB(st.back());
			}
			else
			{
				//find cyc
				while(st.back() != v)
				{
					cyc.PB(st.back());
					st.pop_back();
				}
				cyc.PB(v);
			}
			
			for(auto u : cyc)
			{
			//	cout << u.F << " " << u.S << "\n";
				used[u.F][u.S] = 1;
				add(u.F, u.S);
			}
			//cout << "-----\n";
			for(auto w : cyc)
			{
				for(auto u : from[w.F][w.S])
					if(!used[u.F][u.S])
						dfs(u);
			}
			for(auto u : cyc)
				remove(u.F, u.S);
			assert(cnt == 0);
		}
	}
	
	
	cout << ans << "\n";
	
	return 0;
}