#include <bits/stdc++.h>
using namespace std;
#define rep(i,a,n) for (int i=a;i<n;i++)
#define per(i,a,n) for (int i=n-1;i>=a;i--)
#define pb push_back
#define eb emplace_back
#define mp make_pair
#define all(x) (x).begin(),(x).end()
#define fi first
#define se second
#define SZ(x) ((int)(x).size())
typedef vector<int> VI;
typedef basic_string<int> BI;
typedef long long ll;
typedef pair<int,int> PII;
typedef double db;
mt19937 mrand(random_device{}()); 
const ll mod=1000000007;
int rnd(int x) { return mrand() % x;}
ll powmod(ll a,ll b) {ll res=1;a%=mod; assert(b>=0); for(;b;b>>=1){if(b&1)res=res*a%mod;a=a*a%mod;}return res;}
ll gcd(ll a,ll b) { return b?gcd(b,a%b):a;}
// head

const int N=251000,M=510;
int dx[]={1,-1,0,0},dy[]={0,0,1,-1};
int n,m;
int f[N],cyc[N],rt[N],par[N],tot,tt,l[N],r[N],cnt[N];
char s[M][M];
int id[M][M];
VI e[N];
int find(int x) { return f[x]==x?x:f[x]=find(f[x]); }
void add(int u,int v) {
	//printf("add %d %d\n",u,v);
	if (find(u)==find(v)) {
		while (1) {
			//printf("ccc %d %d\n",v,u);
			cyc[v]=1;
			rt[v]=u;
			if (v==u) break;
			v=par[v];
		}
	} else {
		par[u]=v;
		e[v].pb(u);
		f[find(u)]=find(v);
	}
}

void dfs(int u) {
	l[u]=++tt;
	for (auto v:e[u]) dfs(v);
	r[u]=tt;
}

int main() {
	scanf("%d%d",&n,&m);
	rep(i,0,n) {
		scanf("%s",s[i]);
		rep(j,0,m) if (s[i][j]!='#'&&s[i][j]!='.') {
			id[i][j]=++tot;
			//printf("id %d %d %d\n",tot,i,j);
		}
	}
	rep(i,1,tot+1) f[i]=i;
	rep(i,0,n) rep(j,0,m) {
		if (s[i][j]=='^') {
			if (i>0&&id[i-1][j]>0) add(id[i][j],id[i-1][j]);
		}
		if (s[i][j]=='v') {
			if (i+1<n&&id[i+1][j]>0) add(id[i][j],id[i+1][j]);
		}
		if (s[i][j]=='<') {
			if (j>0&&id[i][j-1]>0) add(id[i][j],id[i][j-1]);
		}
		if (s[i][j]=='>') {
			if (j+1<n&&id[i][j+1]>0) add(id[i][j],id[i][j+1]);
		}
	}
	rep(i,1,tot+1) if (par[i]==0) {
		dfs(i);
	}
	rep(i,0,n) rep(j,0,m) if (s[i][j]=='#') {
		vector<PII> seg;
		rep(d,0,4) {
			int nx=i+dx[d],ny=j+dy[d];
			if (nx>=0&&nx<n&&ny>=0&&ny<m&&id[nx][ny]) {
				int p=id[nx][ny];
				if (cyc[p]) seg.eb(l[rt[p]],r[rt[p]]);
				else seg.eb(l[p],r[p]);
			}
		}
		sort(all(seg));
		int mx=-1;
		for (auto [l,r]:seg) {
			//printf("xx %d %d %d %d\n",i,j,l,r);
			mx=max(mx,l);
			if (mx<=r) {
				cnt[mx]++;
				cnt[r+1]--;
				mx=r+1;
			}
		}
	}
	int ans=0;
	rep(i,1,tot+1) {
		cnt[i]+=cnt[i-1];
		ans=max(ans,cnt[i]);
	}
	printf("%d\n",ans);
}