#include<iostream>
#include<string>
#include<cstdio>
#include<vector>
#include<cmath>
#include<algorithm>
#include<functional>
#include<iomanip>
#include<queue>
#include<ciso646>
#include<random>
#include<map>
#include<set>
#include<bitset>
#include<stack>
#include<unordered_map>
#include<utility>
#include<cassert>
#include<complex>
#include<numeric>
#include<array>
#include<atcoder/dsu>
#include<atcoder/fenwicktree>
#include<atcoder/math>
#include<atcoder/maxflow>

using namespace std;
using namespace atcoder;

//#define int long long
typedef long long ll;

typedef unsigned long long ul;
typedef unsigned int ui;
constexpr ll mod = 1000000007;
const ll INF = mod * mod;
typedef pair<int, int>P;
#define stop char nyaa;cin>>nyaa;
#define rep(i,n) for(int i=0;i<n;i++)
#define per(i,n) for(int i=n-1;i>=0;i--)
#define Rep(i,sta,n) for(int i=sta;i<n;i++)
#define rep1(i,n) for(int i=1;i<=n;i++)
#define per1(i,n) for(int i=n;i>=1;i--)
#define Rep1(i,sta,n) for(int i=sta;i<=n;i++)
#define all(v) (v).begin(),(v).end()
typedef pair<ll, ll> LP;
typedef long double ld;
typedef pair<ld, ld> LDP;
const ld eps = 1e-8;
const ld pi = acosl(-1.0);

ll mod_pow(ll x, ll n, ll m = mod) {
	if (x >= m)x %= m;
	ll res = 1;
	while (n) {
		if (n & 1)res = res * x % m;
		x = x * x % m; n >>= 1;
	}
	return res;
}
struct modint {
	ll n;
	modint() :n(0) { ; }
	modint(ll m) :n(m) {
		if (n >= mod)n %= mod;
		else if (n < 0)n = (n % mod + mod) % mod;
	}
	operator int() { return n; }
};
bool operator==(modint a, modint b) { return a.n == b.n; }
modint operator+=(modint& a, modint b) { a.n += b.n; if (a.n >= mod)a.n -= mod; return a; }
modint operator-=(modint& a, modint b) { a.n -= b.n; if (a.n < 0)a.n += mod; return a; }
modint operator*=(modint& a, modint b) { a.n = ((ll)a.n * b.n) % mod; return a; }
modint operator+(modint a, modint b) { return a += b; }
modint operator-(modint a, modint b) { return a -= b; }
modint operator*(modint a, modint b) { return a *= b; }
modint operator^(modint a, ll n) {
	if (n == 0)return modint(1);
	modint res = (a * a) ^ (n / 2);
	if (n % 2)res = res * a;
	return res;
}

ll inv(ll a, ll p) {
	return (a == 1 ? 1 : (1 - p * inv(p % a, a)) / a + p);
}
modint operator/(modint a, modint b) { return a * modint(inv(b, mod)); }

const int max_n = 1 << 19;
modint fact[max_n], factinv[max_n];
void init_f() {
	fact[0] = modint(1);
	for (int i = 0; i < max_n - 1; i++) {
		fact[i + 1] = fact[i] * modint(i + 1);
	}
	factinv[max_n - 1] = modint(1) / fact[max_n - 1];
	for (int i = max_n - 2; i >= 0; i--) {
		factinv[i] = factinv[i + 1] * modint(i + 1);
	}
}
modint comb(int a, int b) {
	if (a < 0 || b < 0 || a < b)return 0;
	return fact[a] * factinv[b] * factinv[a - b];
}

int gcd(int a, int b) {
	if (a < b)swap(a, b);
	while (b) {
		int r = a % b; a = b; b = r;
	}
	return a;
}

int dx[4] = { 1,0,-1,0 };
int dy[4] = { 0,1,0,-1 };
char mp[100][100];
void solve() {
	int h, w; cin >> h >> w;
	rep(i, h)rep(j, w) {
		cin >> mp[i][j];
	}
	int s = h * w; int t = s + 1;
	mf_graph<int> g(t+1);
	vector<int> frs;
	rep(i, h)rep(j, w) {
		if (mp[i][j] == '#')continue;
		int id = i * w + j;
		if ((i + j) % 2) {
			frs.push_back(s);
			g.add_edge(s, id, 1);
			rep(d, 4) {
				int nx = dx[d] + i;
				int ny = dy[d] + j;
				if (nx < 0 || ny < 0 || nx >= h || ny >= w)continue;
				if (mp[nx][ny] == '#')continue;
				int to = nx * w + ny;
				frs.push_back(id);
				g.add_edge(id, to, 1);
			}
		}
		else {
			frs.push_back(id);
			g.add_edge(id, t, 1);
		}
	}
	int f = g.flow(s,t);
	auto v = g.edges();
	cout << f << "\n";
	//cout << f << " " << v.size() << "\n";
	rep(i, v.size()) {
		auto e = v[i];
		//cout << frs[i] << " " << e.to << " " << e.cap << "\n";
		if (e.flow!=0) {
			if (frs[i] < s&&e.to<s) {
				int x = frs[i] / w, y = frs[i] % w;
				int to = e.to;
				int tx = to / w, ty = to % w;
				if (ty == y + 1) {
					mp[x][y] = '>';
					mp[tx][ty] = '<';
				}
				else if (ty == y - 1) {
					mp[x][y] = '<';
					mp[tx][ty] = '>';
				}
				else if (tx == x + 1) {
					mp[x][y] = 'v';
					mp[tx][ty] = '^';
				}
				else {
					mp[x][y] = '^';
					mp[tx][ty] = 'v';
				}
			}
		}
	}
	rep(i, h) {
		rep(j, w)cout << mp[i][j]; cout << "\n";
	}
}

signed main() {
	ios::sync_with_stdio(false);
	cin.tie(0);
	//cout << fixed << setprecision(15);
	//init_f();
	//init();
	//expr();
	//int t; cin >> t; rep(i, t)
	solve();
	return 0;
}


Measured memory_bytes: 13844