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

void solve([[maybe_unused]] int t){
    const int N = 500;
    
    int r,c;
    cin>>r>>c;
    
    auto id = [&](int x,int y)->int{
        if(x<0 || x>=r || y<0 || y>=c)return -1;
        return x*c+y;
    };
    
    vector mat(r,vector(c,'.'));
    for(int i=0;i<r;i++){
        for(int j=0;j<c;j++){
            cin>>mat[i][j];
        }
    }
    
    const vector<array<int,2>> dir = {{-1,0},{1,0},{0,-1},{0,1}};
    vector succ(r*c,-1);
    for(int i=0;i<r;i++){
        for(int j=0;j<c;j++){
            if(mat[i][j]=='>' && id(i,j+1)!=-1 && mat[i][j+1]!='#' && mat[i][j+1]!='.')succ[id(i,j)]=id(i,j+1);
            if(mat[i][j]=='<' && id(i,j-1)!=-1 && mat[i][j-1]!='#' && mat[i][j-1]!='.')succ[id(i,j)]=id(i,j-1);
            if(mat[i][j]=='^' && id(i-1,j)!=-1 && mat[i-1][j]!='#' && mat[i-1][j]!='.')succ[id(i,j)]=id(i-1,j);
            if(mat[i][j]=='v' && id(i+1,j)!=-1 && mat[i+1][j]!='#' && mat[i+1][j]!='.')succ[id(i,j)]=id(i+1,j);
        }
    }
    
    vector grafo(r*c,vector<int>());
    map<int,int> curr;
    vector vis(r*c,0);
    vector cycle(r*c,false);
    
    for(int i=0;i<r*c;i++){
        if(succ[i]!=-1){
            grafo[succ[i]].push_back(i);
        }
    }
    
    int ans=0;
    
    auto dfs2 = [&](auto &dfs2,int nodo)->void{
        if(vis[nodo]==3)return;
        vis[nodo]++;
        
        if(succ[nodo]!=-1){
            dfs2(dfs2,succ[nodo]);
        }
        
        if(vis[nodo]==1)cycle[nodo]=false;
        else cycle[nodo]=true;
        vis[nodo]=3;
    };
    
    
    for(int i=0;i<r;i++){
        for(int j=0;j<c;j++){
            if(mat[i][j]!='#'&& mat[i][j]!='.'){
                dfs2(dfs2,id(i,j));
            }
        }
    }
    
    auto dfs = [&](auto &dfs,int nodo)->void{
        if(vis[nodo]==3){
            return;
        }
        
        vis[nodo]++;
        
        int x=nodo/c,y=nodo%c;
        
        for(auto [dx,dy] : dir){
            if(id(x+dx,y+dy)!=-1 && mat[x+dx][y+dy]=='#'){
                curr[id(x+dx,y+dy)]++;
            }
        }
        
        ans=max(ans,(int)curr.size());
        
        for(auto i : grafo[nodo]){
            dfs(dfs,i);
        }
        
        for(auto [dx,dy] : dir){
            if(id(x+dx,y+dy)!=-1 && mat[x+dx][y+dy]=='#'){
                curr[id(x+dx,y+dy)]--;
                if(curr[id(x+dx,y+dy)]==0)curr.erase(id(x+dx,y+dy));
            }
        }
    };
    
    vis = vector(r*c,0);
    for(int i=0;i<r;i++){
        for(int j=0;j<c;j++){
            if(mat[i][j]!='#' && mat[i][j]!='.' && (succ[id(i,j)]==-1 || cycle[id(i,j)])){
                dfs(dfs,id(i,j));
            }
        }
    }
    
    cout<<ans<<"\n";
}

int main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    
    int t=1;
    //cin>>t;
    for(int i=1;i<=t;i++)solve(i);
    
    return 0;
}