#include <bits/stdc++.h>

using namespace std;
const int R = 501, N = R * R;
int r, c, n;
int p[N];
string g[R];
vector<int> adj[N], rev[N], cyc[N];
int vis[N], cnt[R][R], in[N], tot, ans, ind;
int dfs1(int u) {
    if (vis[u] == ind) {
        cyc[u].push_back(u);
        return u;
    } else if (vis[u]) {
        return -1;
    }
    if (adj[u].size() == 0) {
        cyc[u].push_back(u);
    }
    vis[u] = ind;
    int t = -1;
    for (int v: adj[u]) {
        t = dfs1(v);
    }
    if (u == t) {
        return -1;
    }
    if (t != -1) {
        cyc[t].push_back(u);
        p[u] = t;
    }
    return t;
}
int f(int x, int y) {
    return x * c + y;
}
int dir[4][2] = {
    {0, 1}, {0, -1}, {-1, 0}, {1, 0}
};
bool check(int x, int y) {
    if (x < 0 || y < 0 || x >= r || y >= c || g[x][y] != '#') {
        return 0;
    }
    return 1;
}
void update(int v, int delta) {
    int i = v / c, j = v % c;
    int ct = 0;
    for (int k = 0; k < 4; k++) {
        int x = i + dir[k][0], y = j + dir[k][1];
        if (check(x, y)) {
            cnt[x][y] += delta;
            if (cnt[x][y] == 0) {
                tot--;
            } else if (cnt[x][y] == 1 && delta > 0) {
                tot++;
            }
        }
    }
}
void dfs2(int u) {
    ans = max(ans, tot);
    for (int v: rev[u]) {
        update(v, 1);
        dfs2(v);
        update(v, -1);
    }
}
int main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cin >> r >> c;
    n = r * c;
    for (int i = 0; i < r; i++) {
        cin >> g[i];
    }
    for (int i = 0; i < r; i++) {
        for (int j = 0; j < c; j++) {
            p[f(i, j)] = -1;
            if (g[i][j] == '<') {
                if (j != 0 && g[i][j - 1] != '.' && g[i][j - 1] != '#') {
                    adj[f(i, j)].push_back(f(i, j - 1));
                }
            } else if (g[i][j] == '>') {
                if (j != c - 1 && g[i][j + 1] != '.' && g[i][j + 1] != '#') {
                    adj[f(i, j)].push_back(f(i, j + 1));
                }
            } else if (g[i][j] == 'v') {
                if (i != r - 1 && g[i + 1][j] != '.' && g[i + 1][j] != '#') {
                    adj[f(i, j)].push_back(f(i + 1, j));
                }
            } else if (g[i][j] == '^') {
                if (i != 0 && g[i - 1][j] != '.' && g[i - 1][j] != '#') {
                    adj[f(i, j)].push_back(f(i - 1, j));
                }
            }
        }
    }
    for (int i = 0; i < n; i++) {
        if (g[i / c][i % c] != '.' && g[i / c][i % c] != '#') {
            ind++;
            dfs1(i);
        }
    }
    for (int i = 0; i < n; i++) {
        if (p[i] == -1) {
            p[i] = i;
        }
    }
    for (int i = 0; i < n; i++) {
        for (int j: adj[i]) {
            if (p[i] != p[j]) {
                rev[p[j]].push_back(p[i]);
                in[p[i]]++;
            }
        }
    }
    for (int i = 0; i < n; i++) {
        if (in[i] == 0 && g[i / c][i % c] != '.' && g[i / c][i % c] != '#') {
            for (int j: cyc[i]) {
                update(j, 1);
            }
            dfs2(i);
            for (int j: cyc[i]) {
                update(j, -1);
            }
        }
    }
    cout << ans << '\n';
    return 0;
}