#include <bits/stdc++.h>


#include <atcoder/all>
using namespace atcoder;

#pragma GCC target("avx2")
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
//#include <boost/multiprecision/cpp_int.hpp>
using namespace std;


using dou =long double;
string yes="yes";
string Yes="Yes";
string YES="YES";
string no="no";
string No="No";
string NO="NO";

template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return true; } return false; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return true; } return false; }
typedef long long ll;
typedef pair<int,int> P;
typedef pair<ll,ll> PL;
const ll mod = 1000000007ll;
//const ll mod = 10000000000ll;
//const ll mod = 10000;

struct mint {
  ll x; // typedef long long ll;
  mint(ll x=0):x((x%mod+mod)%mod){}
  mint operator-() const { return mint(-x);}
  mint& operator+=(const mint a) {
    if ((x += a.x) >= mod) x -= mod;
    return *this;
  }
  mint& operator-=(const mint a) {
    if ((x += mod-a.x) >= mod) x -= mod;
    return *this;
  }
  mint& operator*=(const mint a) { (x *= a.x) %= mod; return *this;}
  mint operator+(const mint a) const { return mint(*this) += a;}
  mint operator-(const mint a) const { return mint(*this) -= a;}
  mint operator*(const mint a) const { return mint(*this) *= a;}
  mint pow(ll t) const {
    if (!t) return 1;
    mint a = pow(t>>1);
    a *= a;
    if (t&1) a *= *this;
    return a;
  }

  // for prime mod
  mint inv() const { return pow(mod-2);}
  mint& operator/=(const mint a) { return *this *= a.inv();}
  mint operator/(const mint a) const { return mint(*this) /= a;}
};
istream& operator>>(istream& is, const mint& a) { return is >> a.x;}
ostream& operator<<(ostream& os, const mint& a) { return os << a.x;}
#define rep(i, n)         for(ll i = 0; i < (ll)(n); i++)
#define brep(n)           for(int bit=0;bit<(1<<n);bit++)
#define bbrep(n)           for(int bbit=0;bbit<(1<<n);bbit++)
#define erep(i,container) for (auto &i : container)
#define itrep(i,container) for (auto i : container)
#define irep(i, n)        for(ll i = n-1; i >= (ll)0ll; i--)
#define rrep(i,m,n) for(ll i = m; i < (ll)(n); i++)
#define reprep(i,j,h,w) rep(i,h)rep(j,w)
#define all(x) (x).begin(),(x).end()
#define rall(x) (x).rbegin(),(x).rend()
#define VEC(type,name,n) std::vector<type> name(n);rep(i,n)std::cin >> name[i];
#define pb push_back
#define pf push_front
#define query int qq;std::cin >> qq;rep(qqq,qq)
#define lb lower_bound
#define ub upper_bound
#define fi first
#define se second
#define itn int
#define mp make_pair
//#define sum(a) accumulate(all(a),0ll)
#define keta fixed<<setprecision
#define vout(a) erep(qxqxqx,a)std::cout << qxqxqx << ' ';std::cout  << std::endl;
#define vvector(name,typ,m,n,a)vector<vector<typ> > name(m,vector<typ> (n,a))
//#define vvector(name,typ,m,n)vector<vector<typ> > name(m,vector<typ> (n))
#define vvvector(name,t,l,m,n,a) vector<vector<vector<t> > > name(l, vector<vector<t> >(m, vector<t>(n,a)));
#define vvvvector(name,t,k,l,m,n,a) vector<vector<vector<vector<t> > > > name(k,vector<vector<vector<t> > >(l, vector<vector<t> >(m, vector<t>(n,a)) ));
#define case std::cout <<"Case #" <<qqq+1<<":"
#define RES(a,i,j) a.resize(i);rep(ii,i)a[ii].resize(j);
#define RESRES(a,i,j,k) a.resize(i);rep(ii,i)a[ii].resize(j);reprep(ii,jj,i,j){dp[ii][jj].resize(k)};
#define res resize
#define as assign
#define ffor for(;;)
#define ppri(a,b) std::cout << a<<" "<<b << std::endl
#define pppri(a,b,c) std::cout << a<<" "<<b <<" "<< c<<std::endl
#define ppppri(a,b,c,d) std::cout << a<<" "<<b <<" "<< c<<' '<<d<<std::endl
#define aall(x,n) (x).begin(),(x).begin()+(n)
#define SUM(a) accumulate(a,0ll) 
#define stirng string
#define gin(a,b) int a,b;std::cin >> a>>b;a--;b--;
#define popcount __builtin_popcount
#define permu(a) next_permutation(all(a))
//#define grid_input(a,type) int h,w;std::cin >> h>>w;vvector(a,type,h,w,0);reprep(i,j,h,w)std::cin >> a[i][j];

//typedef long long T;
ll ceil(ll a,ll b){
    return ((a+b-1)/b);
}
const int INF = 2000000000;
//const ll INF64 =3223372036854775807ll;
//const ll INF64 = 9223372036854775807ll;
const ll INF64 = 9223372036854775ll;
const ll MOD = 1000000007ll;
//const ll MOD = 1000003ll;
const ll OD = 1000000000000007ll;
const dou pi=3.141592653589793;
long long modpow(long long a, long long n,ll MOD) { //累乗の余剰
    long long res = 1;
    while (n > 0) {
        if (n & 1) res = res * a % MOD;
        a = a * a % MOD;
        n >>= 1;
    }
    return res;
}


//メモ
//ゲーム(Grundy数とか)の復習をする
//群論の勉強をする？
//ドツボにハマったら頑張って今までの思考をリセットする
//学会のスライドを作る(水曜日まで)
//周期性の実験をする
//リスニング力をどうにかする
//GT学会の会費を払う
/*
#include <atcoder/all>
using namespace atcoder;
*/
/*
#include <atcoder/all>
using namespace atcoder;
*/

int h,w;
int p(int i,int j){
    return i*w+j;
}
bool hani(int i,int j){//grid上探索において範囲内かどうかをreturn
    if(i>=0&&i<h&&j>=0&&j<w)return true;
    else return false;
}
P re(int n){
    return mp(n/w,n%w);
}
std::vector<int> dd{-1,0,1,0,-1};
int main(){
    
    std::cin >> h>>w;
    vvector(a,char,h,w,0);
    reprep(i,j,h,w)std::cin >> a[i][j];
    mf_graph<int> g(h*w+10);
    int s=h*w;
    int t=h*w+1;
    g.add_edge(s,t,0);
    rep(i,h){
        rep(j,w){
            if((i+j)%2==0){
                //if(a[i][j]!='.')continue;
                g.add_edge(s,p(i,j),1);
                rep(ii,4){
                    int y=i+dd[ii];
                    int x=j+dd[ii+1];
                    if(hani(y,x)&&a[i][j]!='#'&&a[y][x]!='#')g.add_edge(p(i,j),p(y,x),1);
                    else if(hani(y,x))g.add_edge(p(i,j),p(y,x),0);
                }
            }
            else{
                if(a[i][j]=='.')g.add_edge(p(i,j),t,1);
                else g.add_edge(p(i,j),t,0);
            }
            
        }
    }
    std::cout << g.flow(s,t) << std::endl;
    
    vector<mf_graph<int>::edge> ans=g.edges();
    erep(i,ans){
        if(i.from==s||i.to==t)continue;
        if(i.flow==0)continue;
        P p=re(i.from),pp=re(i.to);
        int dy=p.fi-pp.fi;
        int dx=p.se-pp.se;
        if(dy==1){
            a[p.fi][p.se]='^';
            a[pp.fi][pp.se]='v';
        }
        if(dy==-1){
            a[p.fi][p.se]='v';
            a[pp.fi][pp.se]='^';
        }
        if(dx==1){
            a[p.fi][p.se]='<';
            a[pp.fi][pp.se]='>';
        }
        if(dx==-1){
            a[p.fi][p.se]='>';
            a[pp.fi][pp.se]='<';
        }
    }
    rep(i,h){
        rep(j,w){
            std::cout << a[i][j] ;
        }
        std::cout << std::endl;
    }
    
}

Measured memory_bytes: 5664