#include <bits/stdc++.h>
//#define int long long
#define ll long long
#define db double
#define fi first
#define se second
#define pii pair<int,int>
#define vi vector<int>

using namespace std;

const int maxn=500*500; 
int n,m;
char s[505][505]; 
int B[maxn+5]; 
bool flag[maxn+5]; 
int id(int x,int y) {
	return (x-1)*m+y;
}
int dx[4]={-1,1,0,0},dy[4]={0,0,1,-1};
int sign(char c){
	if (c=='^') return 0;
	if (c=='v') return 1; 
	if (c=='>') return 2; 
	if (c=='<') return 3; 
	return -1; 
}
int checkin(int x,int y) {
	return 1<=x && x<=n && 1<=y && y<=m;
}
vector<int> g[maxn+5],h[maxn+5],guan[maxn+5];
int vis[maxn+5],nwans; 
int incir[maxn+5]; 
int sta[maxn+5],top;

void add(int x) {
	for (auto t:guan[x]) {
		B[t]++;
		if (B[t]==1) {
			nwans++; 	
		}	
	}
	
}
void del(int x) {
	for (auto t:guan[x]) {
		B[t]--;
		if (B[t]==0) {
			nwans--; 
		}	
	}
}
int ans;
void dfs(int u,int pre) {
	// <<"**"<<u<<'\n'; 
	if (!incir[u]) {
		add(u); 
	}
	ans=max(ans,nwans);
	vis[u]=1;
	for (auto v:h[u]) {
		if (incir[v]) continue ;
		dfs(v,u);
	}
	if (!incir[u]) {
		del(u); 
	}
}
int main() {
	scanf("%d %d",&n,&m);
	for (int i=1;i<=n;i++){
		scanf("%s",s[i]+1); 
	}
	for (int i=1;i<=n;i++) {
		for (int j=1;j<=m;j++) {
			if (sign(s[i][j])!=-1) {
				flag[id(i,j)]=1; 
				for (int k=0;k<4;k++) {
					int nx=i+dx[k],ny=j+dy[k];
					if (checkin(nx,ny) && s[nx][ny]=='#') guan[id(i,j)].push_back(id(nx,ny)); 
				}
				int tx=i+dx[sign(s[i][j])],ty=j+dy[sign(s[i][j])];
				if (checkin(tx,ty) && sign(s[i][j])!=-1) {
					g[id(i,j)].push_back(id(tx,ty));
					h[id(tx,ty)].push_back(id(i,j)); 
				}
			}
		}
	}
	for (int i=1;i<=n*m;i++) {
		if (!flag[i]) continue ;
		if (vis[i]) continue ;
		int u=i;
		top=0;  
		static vector<int> cir; 
		cir.clear(); 
		while (1) {
			sta[++top]=u; 
			vis[u]=1;
			if (g[u].size()==0) u=0; 
			else u=g[u][0];
			if (!flag[u] || u==0) {
				incir[sta[top]]=1;
				cir.push_back(sta[top]);
				break ;  
			}
			else if (vis[u]) {
				while (sta[top+1]!=u) {
					incir[sta[top]]=1;
					cir.push_back(sta[top]);
					top--; 
				}
				break ; 
			} else ; 
		}
		nwans=0;
		for (auto x:cir) add(x),vis[x]=1; 
	//	cout<<'\n'; 
		for (auto x:cir) {
			dfs(x,-1);
		}
	//	cout<<"**"<<'\n'; 
		for (auto x:cir) del(x); 
	//	cout<<"**"<<'\n'; 
	}
	cout<<ans<<'\n'; 
	return 0;
}