#include<bits/stdc++.h>

using std::cin;
using std::cout;
using ll = long long;
using i128 = __int128;

const int N = 250005;
const int M = 550;

int r, c;
char buf[M][M];
int vis[N];
int p[N];
std::vector<int> v[N], edge[N];

int cnt[N], sum;
int ans = 0;

void inc(int p, int v) {
	sum -= (bool)cnt[p];
	cnt[p] += v;
	sum += (bool)cnt[p];
}

int id(int x, int y) {
	return (x - 1) * c + y;
}
int chk(char c) {
	if(c == '^') return 1;
	if(c == 'v') return 1; 
	if(c == '<') return 1; 
	if(c == '>') return 1; 
	return 0;
}
void dfs0(int x) {
	for(int t : v[x]) {
		inc(t, 1);
	}
	++ vis[x];
	ans = std::max(ans, sum);
	for(int w : edge[x]) if(!vis[w]) {
		dfs0(w);
	}
	--vis[x];
	for(int t : v[x]) {
		inc(t, -1);
	}
}
int main() {
	std::ios::sync_with_stdio(false), cin.tie(0);
	std::vector<std::vector<int>> root;
	cin >> r >> c;
	for(int i = 1;i <= r;++i) {
		for(int j = 1;j <= c;++j) {
			cin >> buf[i][j];
		}
	}
	for(int i = 1;i <= r;++i) {
		for(int j = 1;j <= c;++j) {
			if(buf[i][j] == '.' || buf[i][j] == '#') {
				continue;
			}
			int dx = 0, dy = 0;
			if(buf[i][j] == '^') dx = -1, dy = 0;
			if(buf[i][j] == 'v') dx = 1, dy = 0;
			if(buf[i][j] == '<') dx = 0, dy = -1;
			if(buf[i][j] == '>') dx = 0, dy = 1;
			if(chk(buf[i + dx][j + dy])) {
				p[id(i, j)] = id(i + dx, j + dy);
			} else {
				p[id(i, j)] = id(i, j);
			}
			using pr = std::pair<int, int>;
			for(auto [dx, dy] : {pr{-1, 0}, pr{1, 0}, pr{0, -1}, pr{0, 1}}) {
				if(buf[i + dx][j + dy] == '#') {
					v[id(i, j)].push_back(id(i + dx, j + dy));
				}
			}
		}
	}
	int n = r * c;
	for(int i = 1;i <= n;++i) if(p[i]) {
		if(vis[i]) continue;
		std::vector<int> st;
		int x = i;
		for(;!vis[x];x = p[x]) {
			st.push_back(x);
			vis[x] = 1;
		}
		auto iter = find(st.begin(), st.end(), x);
		if(iter != st.end()) {
			root.emplace_back(iter, st.end());
		}
	}
	memset(vis, 0, sizeof(vis));
	for(int i = 1;i <= n;++i) if(p[i]) edge[p[i]].emplace_back(i);
	for(auto cyc : root) {
		for(int x : cyc) {
			vis[x] = 1;
			for(int d : v[x]) {
				inc(d, 1);
			}
		}
		ans = std::max(ans, sum);
		for(int x : cyc) {
			dfs0(x);
		}
		for(int x : cyc) {
			for(int d : v[x]) {
				inc(d, -1);
			}
		}
	}
	cout << ans << '\n';
}