#pragma GCC optimize("O3")
#include <iostream>
using namespace std;
#include <vector>
#define pb push_back
template<class C> using vc=vector<C>;
#define For(i,a,b) for(int i=(a);i<(b);i++)
#define smax(a,b) a=max(a,b)
#define f first
#define s second
typedef double d;

const int mx=502;
int n,m; char g[mx][mx]; bool x[mx][mx], y[mx][mx], v[mx][mx], V[mx][mx];
int ans, cur;
void solve(int i, int j)
{
    bool a0=0,a1=0,a2=0,a3=0;
    if(y[i-1][j]&&!v[i-1][j]) a0=1, v[i-1][j]=1, cur++;
    if(y[i+1][j]&&!v[i+1][j]) a1=1, v[i+1][j]=1, cur++;
    if(y[i][j-1]&&!v[i][j-1]) a2=1, v[i][j-1]=1, cur++;
    if(y[i][j+1]&&!v[i][j+1]) a3=1, v[i][j+1]=1, cur++;
    ans=max(ans,cur), V[i][j]=1;
    if(g[i-1][j]=='v') solve(i-1,j);
    if(g[i+1][j]=='^') solve(i+1,j);
    if(g[i][j-1]=='>') solve(i,j-1);
    if(g[i][j+1]=='<') solve(i,j+1);
    if(a0) v[i-1][j]=0, cur--;
    if(a1) v[i+1][j]=0, cur--;
    if(a2) v[i][j-1]=0, cur--;
    if(a3) v[i][j+1]=0, cur--;
}
int main()
{
    cin.sync_with_stdio(0), cin.tie(0), cout.sync_with_stdio(0), cout.tie(0);
    cin>>n>>m, n+=2, m+=2;
    For(i,0,n) For(j,0,m) g[i][j]='.', x[i][j]=1;
    For(i,1,n-1) For(j,1,m-1) cin>>g[i][j],
        y[i][j]=g[i][j]=='#', x[i][j]=g[i][j]=='.'||y[i][j];
    For(i,0,n) For(j,0,m)
    {
        if(V[i][j]) continue;
        if(g[i][j]=='>') if(x[i][j+1]) solve(i,j);
        if(g[i][j]=='<') if(x[i][j-1]) solve(i,j);
        if(g[i][j]=='^') if(x[i-1][j]) solve(i,j);
        if(g[i][j]=='v') if(x[i+1][j]) solve(i,j);
    }
    cout<<ans<<'\n';
}