#include <bits/stdc++.h>

#ifdef DEBUG
#include <Mylib/Debug/debug.cpp>
#else
#define dump(...) ((void)0)
#endif

template <typename T, typename U>
bool chmin(T &a, const U &b){
  return (a > b ? a = b, true : false);
}

template <typename T, typename U>
bool chmax(T &a, const U &b){
  return (a < b ? a = b, true : false);
}

template <typename T, size_t N, typename U>
void fill_array(T (&a)[N], const U &v){
  std::fill((U*)a, (U*)(a + N), v);
}

template <typename T, size_t N, size_t I = N>
auto make_vector(const std::array<int, N> &a, T value = T()){
  static_assert(I >= 1);
  static_assert(N >= 1);
  if constexpr (I == 1){
    return std::vector<T>(a[N - I], value);
  }else{
    return std::vector(a[N - I], make_vector<T, N, I - 1>(a, value));
  }
}

template <typename T>
std::ostream& operator<<(std::ostream &s, const std::vector<T> &a){
  for(auto it = a.begin(); it != a.end(); ++it){
    if(it != a.begin()) s << " ";
    s << *it;
  }
  return s;
}

template <typename T>
std::istream& operator>>(std::istream &s, std::vector<T> &a){
  for(auto &x : a) s >> x;
  return s;
}

/**
 * @title Ford-Fulkerson algorithm
 * @docs ford_fulkerson.md
 */
namespace haar_lib {
  template <typename T>
  class ford_fulkerson {
  public:
    struct edge {
      int from, to, rev;
      T cap;
      bool is_rev;
    };

  private:
    int size;

    std::vector<std::vector<edge>> graph;
    std::vector<bool> visit;

    T dfs(int from, int to, T flow){
      if(from == to) return flow;
      visit[from] = true;

      for(auto &e : graph[from]){
        if(!visit[e.to] and e.cap > 0){
          T d = dfs(e.to, to, std::min(flow, e.cap));
          if(d > 0){
            e.cap -= d;
            graph[e.to][e.rev].cap += d;
            return d;
          }
        }
      }
      return 0;
    }

  public:
    ford_fulkerson(){}
    ford_fulkerson(int size): size(size), graph(size), visit(size){}

    void add_edge(int from, int to, const T &cap){
      graph[from].push_back({from, to, (int)graph[to].size(), cap, false});
      graph[to].push_back({to, from, (int)graph[from].size() - 1, 0, true});
    }

    void reset_flow(){
      for(auto &v : graph){
        for(auto &e : v){
          if(e.is_rev){
            graph[e.to][e.rev].cap += e.cap;
            e.cap = 0;
          }
        }
      }
    }

    T solve(int s, int t){
      T ret = 0;

      while(1){
        visit.assign(size, false);
        T flow = dfs(s, t, std::numeric_limits<T>::max());
        if(flow == 0) return ret;
        ret += flow;
      }
    }

    std::vector<edge> edges() const {
      std::vector<edge> ret;
      for(auto &v : graph) ret.insert(ret.end(), v.begin(), v.end());
      return ret;
    }
  };
}


namespace haar_lib {}

namespace solver {
  using namespace haar_lib;

  void init(){
    std::cin.tie(0);
    std::ios::sync_with_stdio(false);
    std::cout << std::fixed << std::setprecision(12);
    std::cerr << std::fixed << std::setprecision(12);
    std::cin.exceptions(std::ios_base::failbit);
  }

  int dir[4][2] = {{1, 0}, {-1, 0}, {0, 1}, {0, -1}};

  void solve(){
    int N, M; std::cin >> N >> M;
    std::vector<std::string> S(N); std::cin >> S;

    ford_fulkerson<int> mf(N * M * 2 + 2);

    int s, t;
    auto index = make_vector<int, 2>({N, M});
    auto rev = std::vector<std::pair<int, int>>(N * M);

    {
      int k = 0;

      for(int i = 0; i < N; ++i){
        for(int j = 0; j < M; ++j){
          index[i][j] = k++;
          rev[index[i][j]] = std::make_pair(i, j);
        }
      }

      s = k++;
      t = k++;
    }

    for(int i = 0; i < N; ++i){
      for(int j = 0; j < M; ++j){
        if(S[i][j] == '#') continue;
        if((i + j) % 2 == 0){
          mf.add_edge(s, index[i][j], 1);
        }else{
          mf.add_edge(index[i][j], t, 1);
        }
      }
    }

    for(int i = 0; i < N; ++i){
      for(int j = 0; j < M; ++j){
        if((i + j) % 2 == 1 or S[i][j] == '#') continue;
        for(auto [dx, dy] : dir){
          int x = i + dx, y = j + dy;
          if(x < 0 or x >= N or y < 0 or y >= M or S[x][y] == '#') continue;
          mf.add_edge(index[i][j], index[x][y], 1);
        }
      }
    }

    std::cout << mf.solve(s, t) << "\n";

    auto edges = mf.edges();
    for(auto &e : edges){
      if(e.cap == 0 and e.from != s and e.to != t and not e.is_rev){
        auto [x1, y1] = rev[e.from];
        auto [x2, y2] = rev[e.to];

        if(x1 == x2){
          if(y1 == y2 + 1){
            S[x1][y1] = '<';
            S[x1][y2] = '>';
          }else{
            S[x1][y1] = '>';
            S[x1][y2] = '<';
          }
        }else{
          if(x1 == x2 + 1){
            S[x1][y1] = '^';
            S[x2][y2] = 'v';
          }else{
            S[x1][y1] = 'v';
            S[x2][y2] = '^';
          }
        }
      }
    }

    for(int i = 0; i < N; ++i) std::cout << S[i] << "\n";
  }
}

int main(){
  solver::init();
  while(true){
    try{
      solver::solve();
    }catch(const std::istream::failure &e){
      break;
    }
  }
  return 0;
}


Measured memory_bytes: 7276