#pragma GCC optimize("Ofast")
#pragma GCC optimize("unroll-loops")

#include <bits/stdc++.h>

using namespace std;
typedef long long ll;

const int N = 500 + 4;
const int MOD = 1e9 + 7 ;

int n, m;

char a[N][N] ;

int vis[N*N + 3];

int dx[]={0,0,1,-1};
int dy[]={1,-1,0,0};

int adj[N*N + 10] ;

vector<int> ad[N*N + 10] ;

int ind[N][N] ;
int x[N*N + 3] , y[N*N + 3];


void add_cycle(int root){
    int cur= adj[root];
    while(cur != root){
        ind[x[cur]][y[cur]]= root;
        cur= adj[cur];
    }
}

void dfs1(int node){
    vis[node]= 1;
    int nxt= adj[node];
    if(!vis[nxt]){
        dfs1(nxt);
    }else if(vis[nxt] == 1){
        add_cycle(nxt);
    }
    vis[node]= 2;
}


vector< pair<int ,int > > gr[N*N + 3] ;


bool taken[N][N] ;

vector<pair<int ,int > > by_me[N*N] ;

vector<int> is_r(N*N +  4 , 1) ;

int dfs(int i , int p = -1)
{

    int sc =0 ;

    for(auto ch : gr[i] )
    {
        if( !taken[ch.first][ch.second] )
        {
            sc++ ;
            taken[ch.first][ch.second] =1 ;

            by_me[i].push_back(ch) ;
        }
    }

    int te =0 ;

    for(int ch : ad[i] )
    {
        if(ch == p) continue;

        te = max(te , dfs(ch , i) ) ;
    }

    sc += te ;

    for(auto ch : by_me[i])
    {
        taken[ch.first][ch.second] = 0 ;
    }

    return sc ;
}

int main()
{
    cin.tie(0);cin.sync_with_stdio(0);
    cout.tie(0);cout.sync_with_stdio(0);


    cin >> n >> m;

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

    for (int i = 1; i <= n; ++i) {
        for (int j = 1; j <= m; ++j) {
            cin >> a[i][j] ;
        }
    }

    memset(ind , -1 , sizeof ind) ;
    memset(adj , -1 , sizeof -1) ;


    for(int i =1 ; i <= n; i++)
    {
        for (int j = 1; j <= m; ++j) {

            if(a[i][j] != '.' && a[i][j] != '#')
            {
                ind[i][j] = (i-1)*m + j ;
                x[ (i-1)*m + j ] = i ;
                y[ (i-1)*m + j] = j ;
            }

        }
    }

    for (int i = 1; i <= n; ++i) {

        for(int j =1 ; j <= m; j++)
        {
            if (a[i][j] == '>' &&   ~ind[i][j+1]   ) {

                adj[ ind[i][j] ] =  ind[i][j+1] ;

            } else if (a[i][j] == 'v' && ~ind[i+1][j] ) {

                adj[ ind[i][j] ] =  ind[i+1][j] ;

            } else if (a[i][j] == '<' && ~ind[i][j-1] ) {

                adj[ ind[i][j] ] =  ind[i][j-1] ;

            } else if( a[i][j] == '^' && ~ind[i-1][j] ) {

                adj[ ind[i][j] ] =  ind[i-1][j] ;
            }

        }
    }

    for(int i= 1;  i <= n ; i++)
    {
        for(int j =1 ; j <= m; j+=1)
        {
            if(~ind[i][j] && vis[(i-1)*m + j ] == 0) dfs1( (i-1)*m + j ) ;
        }
    }

    for (int i = 1; i <= n; ++i) {

        for(int j =1 ; j <= m; j++)
        {

            if (a[i][j] == '>' &&   ~ind[i][j+1] && ind[i][j+1] != ind[i][j]  ) {

                ad[ ind[i][j+1] ].push_back(ind[i][j] ) ;
                is_r[ind[i][j]] = 0 ;

            } else if (a[i][j] == 'v' && ~ind[i+1][j] && ind[i+1][j] != ind[i][j] ) {

                ad[ ind[i+1][j] ].push_back(ind[i][j] ) ;
                is_r[ind[i][j]] = 0 ;

            } else if (a[i][j] == '<' && ~ind[i][j-1] && ind[i][j-1] != ind[i][j] ) {

                ad[ ind[i][j-1] ].push_back(ind[i][j] ) ;
                is_r[ind[i][j]] = 0 ;

            } else if( a[i][j] == '^' && ~ind[i-1][j] && ind[i-1][j] != ind[i][j]) {

                ad[ ind[i-1][j] ].push_back(ind[i][j] ) ;

                is_r[ind[i][j]] = 0 ;
            }



        }
    }



    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) {
                    if( ~ind[i+dx[k]][j + dy[k]] ) gr[ ind[i+dx[k]][j+dy[k]] ].push_back({i , j} ) ;
                }
            }
        }
    }


    for(int i = 0 ; i <= N * N  ; i++) sort( gr[i].begin() , gr[i].end() ) , gr[i].erase(unique(gr[i].begin() , gr[i].end()) , gr[i].end()) ;


    int ans =0 ;

    for(int i =1; i <= n; i++)
    {
        for(int j= 1; j <= m; j++)
        {
            int id = (i-1)*(m) + j;

            if(is_r[id] && ~ind[i][j] && ind[i][j] == id) ans = max(ans , dfs(id)  ) ;
        }
    }

    cout << ans ;

    return 0;
}