#include <iostream>
#include <vector>
#include <string>
using namespace std ;
int r, c ;
string b ;
int d[4] ;
int cd[256] ;
int main() {
   cin >> r >> c ;
   string s ;
   for (int i=0; i<=c; i++)
      b.push_back('$') ;
   for (int i=0; i<r; i++) {
      cin >> s ;
      b += s ;
      b.push_back('$') ;
   }
   for (int i=0; i<=c; i++)
      b.push_back('$') ;
   d[0] = -c-1 ;
   d[1] = -1 ;
   d[2] = 1 ;
   d[3] = c+1 ;
   for (int i=0; i<256; i++)
      cd[i] = -1 ;
   cd[(int)'^'] = 0 ;
   cd[(int)'<'] = 1 ;
   cd[(int)'>'] = 2 ;
   cd[(int)'v'] = 3 ;
   vector<int> typ(b.size()) ;
   vector<int> path ;
   for (int i=0; i<=(int)b.size(); i++)
      if (cd[(int)b[i]] >= 0 && typ[i] == 0) {
         int at = i ;
         path.clear() ;
         while (1) {
            typ[at] = -1 ;
            path.push_back(at) ;
            int nxt = at + d[cd[(int)b[at]]] ;
            if (cd[(int)b[nxt]] < 0) {
               typ[at] = -4 ;
               path.pop_back() ;
               break ;
            }
            if (typ[nxt] == -1) { // new loop
               while (1) {
                  at = path[path.size()-1] ;
                  path.pop_back() ;
                  typ[at] = -3 ;
                  if (at == nxt)
                     break ;
               }
               typ[at] = -5 ;
               break ;
            } else if (typ[nxt] != 0) { // ran into something explored
               break ;
            }
            at = nxt ;
         }
         for (auto v: path)
            typ[v] = -2 ;
      }
   vector<int> cnts(b.size()) ;
   vector<int> st ;
   int cnt = 0 ;
   int best = 0 ;
   auto visit = [&](int at) {
      for (int i=0; i<4; i++) {
         int dst = at + d[i] ;
         if (b[dst] == '#') {
            if (cnts[dst]++ == 0)
               cnt++ ;
         }
      }
      best = max(best, cnt) ;
   } ;
   auto unvisit = [&](int at) {
      for (int i=0; i<4; i++) {
         int dst = at + d[i] ;
         if (b[dst] == '#') {
            if (--cnts[dst] == 0)
               cnt-- ;
         }
      }
   } ;
   for (int i=0; i<(int)b.size(); i++)
      if (typ[i] <= -4) {
         path.clear() ;
         int at = i ;
         if (typ[at] == -5) {
            while (1) {
               at += d[cd[(int)b[at]]] ;
               visit(at) ;
               st.push_back(at) ;
               if (typ[at] == -5) {
                  st.push_back(0) ;
                  break ;
               } else {
                  st.push_back(5) ;
               }
            }
         } else {
            visit(at) ;
            st.push_back(at) ;
            st.push_back(0) ;
         }
         while (st.size() > 0) {
            int dd = st[st.size()-1] ;
            at = st[st.size()-2] ;
            if (dd > 3) {
               unvisit(at) ;
               st.pop_back() ;
               st.pop_back() ;
               continue ;
            }
            st[st.size()-1] = dd + 1 ;
            int dst = at - d[dd] ;
            if (typ[dst] != -5 && cd[(int)b[dst]] != -1 &&
                at == dst + d[cd[(int)b[dst]]]) {
               visit(dst) ;
               st.push_back(dst) ;
               st.push_back(0) ;
            }
         }
      }
   cout << best << endl ;
}