#include <string>
#include <bits/functexcept.h>
#include <iosfwd>
#include <bits/cxxabi_forced.h>
#include <bits/functional_hash.h>

#pragma push_macro("__SIZEOF_LONG__")
#pragma push_macro("__cplusplus")
#define __SIZEOF_LONG__ __SIZEOF_LONG_LONG__
#define unsigned unsigned long
#define __cplusplus 201102L

#define __builtin_popcountl __builtin_popcountll
#define __builtin_ctzl __builtin_ctzll

#include <bitset>

#pragma pop_macro("__cplusplus")
#pragma pop_macro("__SIZEOF_LONG__")
#undef unsigned
#undef __builtin_popcountl
#undef __builtin_ctzl

#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 opz(r*c,bitset<N*N>());
    
    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);
            
            for(auto [dx,dy] : dir){
                if(id(i+dx,j+dy)!=-1 && mat[i+dx][j+dy]=='#'){
                    opz[id(i,j)][id(i+dx,j+dy)]=1;
                }
            }
        }
    }
    vector vis(r*c,0);
    
    auto dfs = [&](auto &dfs,int nodo)->void{
        if(vis[nodo]==3)return;
        vis[nodo]++;
        
        if(succ[nodo]!=-1){
            dfs(dfs,succ[nodo]);
            opz[nodo]|=opz[succ[nodo]];
        }
        
        vis[nodo]=3;
    };
    
    int ans=0;
    for(int i=0;i<r;i++){
        for(int j=0;j<c;j++){
            if(mat[i][j]!='#'&& mat[i][j]!='.'){
                dfs(dfs,id(i,j));
                ans=max(ans,(int)opz[id(i,j)].count());
            }
        }
    }
    
    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;
}