#include <bits/stdc++.h>
using namespace std;

char ch[509][509];
vector <int> v[250009], adj[250009];
int cudi[250009], msh[250009];
int been[250009], cik[250009];
int bo[250009], comp, id[509][509];
int cnt[250009];
int ans, PAS;

void dfs(int i){
    bo[i] = 1;
    if(cik[i] != comp || cik[i] == i){
        for(auto x:v[i]){
            if(cnt[x] == 0) ans++;
            cnt[x]++;
        }
    }

    PAS = max(PAS, ans);

    //cout << i << " " << ans << "\n";

    for(auto x:adj[i]){
        if(bo[x] == 1) continue;
        dfs(x);
    }

    if(cik[i] != comp || cik[i] == i){
        for(auto x:v[i]){
            if(cnt[x] == 1) ans--;
            cnt[x]--;
        }
    }
}

char yle[250009];

int main(){
    ios_base::sync_with_stdio(false),cin.tie(0),cout.tie(0);
    int n, m;
    cin >> n >> m;
    for(int i = 1; i <= n; i++){
        string s;
        cin >> s;
        for(int j = 1; j <= m; j++){
            ch[i][j] = s[j - 1];
            id[i][j] = (i - 1) * m + j;
            yle[id[i][j]] = ch[i][j];
        }
    }

    for(int i = 1; i <= n; i++){
        for(int j = 1; j <= m; j++){
            int ii, jj;
            if(ch[i][j] == '<'){
                ii = i; jj = j - 1;
                msh[id[i][j]] = id[ii][jj];
            }

            if(ch[i][j] == '^'){
                ii = i - 1; jj = j;
                msh[id[i][j]] = id[ii][jj];
            }

            if(ch[i][j] == '>'){
                ii = i; jj = j + 1;
                msh[id[i][j]] = id[ii][jj];
            }

            if(ch[i][j] == 'v'){
                ii = i + 1; jj = j;
                msh[id[i][j]] = id[ii][jj];
            }

            if(ch[i][j] == '#'){
                v[id[i - 1][j]].push_back(id[i][j]);
                v[id[i + 1][j]].push_back(id[i][j]);
                v[id[i][j - 1]].push_back(id[i][j]);
                v[id[i][j + 1]].push_back(id[i][j]);
            }

            if(ch[i][j] == '#' || ch[i][j] == '.')
                cudi[id[i][j]] = 1;
        }
    }

    for(int i = 1; i <= n * m; i++){
        if(yle[msh[i]] == '#' || yle[msh[i]] == '.') msh[i] = 0;
    }

    for(int i = 1; i <= n * m; i++){
        if(cudi[i]) continue;
        if(msh[i] != 0) adj[msh[i]].push_back(i);

        int c = i;
        while(c && !been[c]){
            been[c] = i;
            int e = c;
            c = msh[c];
            if(been[c] == i){
                int d = c;
                int xo = d;
                cik[d] = xo;
                while(d != e){
                    d = msh[d];
                    cik[d] = xo;
                    for(auto x: v[d]){
                        v[xo].push_back(x);
                    }
                }
                break;
            }

            if(c == 0){
                cik[e] = e;
            }
        }
    }

    for(int i = 1; i <= n * m; i++){
        if(cik[i] != i) continue;
        if(bo[i]) continue;
        comp = i;
        ans = 0;
        dfs(i);
    }

    cout << PAS;

    return 0;
}