#pragma region template
#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
using ll = long long;
using ull = unsigned long long;
using ld = long double;
using vi = vector<int>;
using vvi = vector<vi>;
using vvvi = vector<vvi>;
using vll = vector<ll>;
using vvll = vector<vll>;
using vvvll = vector<vvll>;
using vld = vector<ld>;
using vvld = vector<vld>;
using vvvld = vector<vvld>;
using vs = vector<string>;
using pll = pair<ll, ll>;
using vp = vector<pll>;
template <typename T>
using pqrev = priority_queue<T, vector<T>, greater<T>>;
#define rep(i, n) for (ll i = 0, i##_end = (n); i < i##_end; i++)
#define repb(i, n) for (ll i = (n)-1; i >= 0; i--)
#define repr(i, a, b) for (ll i = (a), i##_end = (b); i < i##_end; i++)
#define reprb(i, a, b) for (ll i = (b)-1, i##_end = (a); i >= i##_end; i--)
#define ALL(a) (a).begin(), (a).end()
#define SZ(x) ((ll)(x).size())
//*
constexpr ll MOD = 1e9 + 7;
/*/
constexpr ll MOD = 998244353;
//*/
constexpr ll INF = 1e+18;
constexpr ld EPS = 1e-12L;
constexpr ld PI = 3.14159265358979323846L;
constexpr ll GCD(ll a, ll b) { return b ? GCD(b, a % b) : a; }
constexpr ll LCM(ll a, ll b) { return a / GCD(a, b) * b; }
template <typename S, typename T>
constexpr bool chmax(S &a, const T &b) {
  if (a < b) {
    a = b;
    return 1;
  }
  return 0;
}
template <typename S, typename T>
constexpr bool chmin(S &a, const T &b) {
  if (b < a) {
    a = b;
    return 1;
  }
  return 0;
}
#ifdef OJ_LOCAL
#include "dump.hpp"
#else
#define dump(...) ((void)0)
#endif
template <typename T>
bool print_(const T &a) {
  cout << a;
  return true;
}
template <typename T>
bool print_(const vector<T> &vec) {
  for (auto &a : vec) {
    cout << a;
    if (&a != &vec.back()) {
      cout << " ";
    }
  }
  return false;
}
template <typename T>
bool print_(const vector<vector<T>> &vv) {
  for (auto &v : vv) {
    for (auto &a : v) {
      cout << a;
      if (&a != &v.back()) {
        cout << " ";
      }
    }
    if (&v != &vv.back()) {
      cout << "\n";
    }
  }
  return false;
}
void print() { cout << "\n"; }
template <typename Head, typename... Tail>
void print(Head &&head, Tail &&... tail) {
  bool f = print_(head);
  if (sizeof...(tail) != 0) {
    cout << (f ? " " : "\n");
  }
  print(forward<Tail>(tail)...);
}
#pragma endregion

void Pr(bool f){
  cout << (f ? "Yes" : "No") << "\n";
  exit(0);
}

int main() {
  cin.tie(0);
  ios::sync_with_stdio(false);
  cout << fixed << setprecision(20);
  ll n, m;
  cin >> n >> m;
  auto id = [&](ll i, ll j) -> ll {
    return i*m+j;
  };
  vs s(n);
  rep(i, n){
    cin >> s[i];
  }
  mf_graph<int> g(n*m+2);
  rep(i, n)rep(j, m){
    if((i+j)&1){
      g.add_edge(id(i, j), n*m+1, 1);
      continue;
    }else{
      g.add_edge(n*m, id(i, j), 1);
    }
    if(s[i][j]=='#') continue;
    if(i>0 && s[i-1][j]=='.') g.add_edge(id(i, j), id(i-1, j), 1);
    if(i<n-1 && s[i+1][j]=='.') g.add_edge(id(i, j), id(i+1, j), 1);
    if(j>0 && s[i][j-1]=='.') g.add_edge(id(i, j), id(i, j-1), 1);
    if(j<m-1 && s[i][j+1]=='.') g.add_edge(id(i, j), id(i, j+1), 1);
  }
  auto ans = g.flow(n*m, n*m+1);
  auto res = g.edges();
  for(auto&& e: res){
    if(e.from==n*m) continue;
    if(e.to==n*m+1) continue;
    if(e.flow==0) continue;
    ll z = e.to-e.from;
    if(z==1){
      s[e.from/m][e.from%m] = '>';
      s[e.to/m][e.to%m] = '<';
    }
    if(z==-1){
      s[e.from/m][e.from%m] = '<';
      s[e.to/m][e.to%m] = '>';
    }
    if(z==m){
      s[e.from/m][e.from%m] = 'v';
      s[e.to/m][e.to%m] = '^';
    }
    if(z==-m){
      s[e.from/m][e.from%m] = '^';
      s[e.to/m][e.to%m] = 'v';
    }
  }
  print(ans);
  for(auto&& e: s){
    print(e);
  }
}


Measured memory_bytes: 5604