#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef pair<int, int> pii;
// mt19937 g(chrono::high_resolution_clock::now().time_since_epoch().count());

const int cx[] = {-1, 1, 0, 0};
const int cy[] = {0, 0, -1, 1};

int N, M, ans, now;
char a[505][505];
int c[505][505];
pii nxt[505][505];
int wtr[505][505], vis[505][505], incyc[505][505];
vector<pii> redg[505][505], sgt[505][505];

void DFS(int x, int y) {
    if(incyc[x][y]) return;
    for(auto [a, b]: sgt[x][y]) {
        c[a][b]++;
        if(c[a][b] == 1)    now++;
    }
    ans = max(ans, now);
    for(auto [a, b]: redg[x][y])
        DFS(a, b);

    for(auto [a, b]: sgt[x][y]) {
        c[a][b]--;
        if(c[a][b] == 0)    now--;
    }
}

void solve_test() {
    scanf("%d%d\n", &N, &M);
    for(int i = 1; i <= N; i++) {
        scanf("%s", a[i] + 1);
    }

    for(int i = 0; i <= N + 1; i++) a[i][0] = a[i][M + 1] = '.';
    for(int j = 0; j <= M + 1; j++) a[0][j] = a[N + 1][j] = '.';

    for(int i = 1; i <= N; i++)
        for(int j = 1; j <= M; j++) {
            if(a[i][j] == '#') {
                for(int k = 0; k < 4; k++)
                    sgt[i + cx[k]][j + cy[k]].push_back({i, j});
            } else if(a[i][j] == '<') {
                nxt[i][j] = {i, j - 1};
                redg[i][j - 1].push_back({i, j});
                wtr[i][j] = 1;
            } else if(a[i][j] == '>') {
                nxt[i][j] = {i, j + 1};
                redg[i][j + 1].push_back({i, j});
                wtr[i][j] = 1;
            } else if(a[i][j] == '^') {
                nxt[i][j] = {i - 1, j};
                redg[i - 1][j].push_back({i, j});
                wtr[i][j] = 1;
            } else if(a[i][j] == 'v') {
                nxt[i][j] = {i + 1, j};
                redg[i + 1][j].push_back({i, j});
                wtr[i][j] = 1;
            }
        }

    ans = 0; now = 0;
    for(int i = 1; i <= N; i++)
        for(int j = 1; j <= M; j++)
            if(wtr[i][j]) {
                int x, y;
                tie(x, y) = nxt[i][j];
                if(wtr[x][y])   continue;

                DFS(i, j);
            }

    int I = 0;
    for(int i = 1; i <= N; i++)
        for(int j = 1; j <= M; j++)
            if(wtr[i][j] && !vis[i][j]) {
                I++;
                int x = i, y = j;
                while(wtr[x][y] && !vis[x][y]) {
                    vis[x][y] = I;
                    tie(x, y) = nxt[x][y];
                }
                if(wtr[x][y] && vis[x][y] == I) {
                    int xx = x, yy = y;
                    vector<pii> cyc;
                    cyc.push_back({x, y});
                    tie(x, y) = nxt[x][y];
                    while(x != xx || y != yy) {
                        cyc.push_back({x, y});
                        tie(x, y) = nxt[x][y];
                    }

                    now = 0;
                    for(auto [x, y]: cyc) {
                        incyc[x][y] = 1;
                        for(auto [a, b]: sgt[x][y]) {
                            c[a][b]++;
                            if(c[a][b] == 1)    now++;
                        }
                    }

                    ans = max(ans, now);

                    for(auto [x, y]: cyc) {
                        for(auto [a, b]: redg[x][y])
                            DFS(a, b);
                    }

                    for(auto [x, y]: cyc) {
                        incyc[x][y] = 1;
                        for(auto [a, b]: sgt[x][y]) {
                            c[a][b]--;
                            if(c[a][b] == 0)    now--;
                        }
                    }
                }
            }

    printf("%d\n", ans);
}

int main() {
#ifdef USEFOPEN
    freopen("1.in", "r", stdin);
    //freopen("1.out", "w", stdout);
#endif

    cin.sync_with_stdio(false); cin.tie(0);

    int T = 1;
//    scanf("%d", &T);
    for(int t = 1; t <= T; t++) {
        //printf("Case #%d: ", t);
        solve_test();
    }

    return 0;
}