#define _CRT_SECURE_NO_WARNINGS
#include <bits/stdc++.h>
#include <unordered_map>

using namespace std;

typedef long long ll;

template <class Cap> struct mf_graph {
public:
    mf_graph() : _n(0) {}
    mf_graph(int n) : _n(n), g(n) {}

    int add_edge(int from, int to, Cap cap) {
        assert(0 <= from && from < _n);
        assert(0 <= to && to < _n);
        assert(0 <= cap);
        int m = int(pos.size());
        pos.push_back({ from, int(g[from].size()) });
        g[from].push_back(_edge{ to, int(g[to].size()), cap });
        g[to].push_back(_edge{ from, int(g[from].size()) - 1, 0 });
        return m;
    }

    struct edge {
        int from, to;
        Cap cap, flow;
    };

    edge get_edge(int i) {
        int m = int(pos.size());
        assert(0 <= i && i < m);
        auto _e = g[pos[i].first][pos[i].second];
        auto _re = g[_e.to][_e.rev];
        return edge{ pos[i].first, _e.to, _e.cap + _re.cap, _re.cap };
    }
    std::vector<edge> edges() {
        int m = int(pos.size());
        std::vector<edge> result;
        for (int i = 0; i < m; i++) {
            result.push_back(get_edge(i));
        }
        return result;
    }
    void change_edge(int i, Cap new_cap, Cap new_flow) {
        int m = int(pos.size());
        assert(0 <= i && i < m);
        assert(0 <= new_flow && new_flow <= new_cap);
        auto& _e = g[pos[i].first][pos[i].second];
        auto& _re = g[_e.to][_e.rev];
        _e.cap = new_cap - new_flow;
        _re.cap = new_flow;
    }

    Cap flow(int s, int t) {
        return flow(s, t, std::numeric_limits<Cap>::max());
    }
    Cap flow(int s, int t, Cap flow_limit) {
        assert(0 <= s && s < _n);
        assert(0 <= t && t < _n);

        std::vector<int> level(_n), iter(_n);
        queue<int> que;

        auto bfs = [&]() {
            std::fill(level.begin(), level.end(), -1);
            level[s] = 0;
            while(!que.empty())
                que.pop();
            que.push(s);
            while (!que.empty()) {
                int v = que.front();
                que.pop();
                for (auto e : g[v]) {
                    if (e.cap == 0 || level[e.to] >= 0) continue;
                    level[e.to] = level[v] + 1;
                    if (e.to == t) return;
                    que.push(e.to);
                }
            }
        };
        auto dfs = [&](auto self, int v, Cap up) {
            if (v == s) return up;
            Cap res = 0;
            int level_v = level[v];
            for (int& i = iter[v]; i < int(g[v].size()); i++) {
                _edge& e = g[v][i];
                if (level_v <= level[e.to] || g[e.to][e.rev].cap == 0) continue;
                Cap d =
                    self(self, e.to, std::min(up - res, g[e.to][e.rev].cap));
                if (d <= 0) continue;
                g[v][i].cap += d;
                g[e.to][e.rev].cap -= d;
                res += d;
                if (res == up) break;
            }
            return res;
        };

        Cap flow = 0;
        while (flow < flow_limit) {
            bfs();
            if (level[t] == -1) break;
            std::fill(iter.begin(), iter.end(), 0);
            while (flow < flow_limit) {
                Cap f = dfs(dfs, t, flow_limit - flow);
                if (!f) break;
                flow += f;
            }
        }
        return flow;
    }

    std::vector<bool> min_cut(int s) {
        std::vector<bool> visited(_n);
        queue<int> que;
        que.push(s);
        while (!que.empty()) {
            int p = que.front();
            que.pop();
            visited[p] = true;
            for (auto e : g[p]) {
                if (e.cap && !visited[e.to]) {
                    visited[e.to] = true;
                    que.push(e.to);
                }
            }
        }
        return visited;
    }

private:
    int _n;
    struct _edge {
        int to, rev;
        Cap cap;
    };
    std::vector<std::pair<int, int>> pos;
    std::vector<std::vector<_edge>> g;
};

void solve() {
    int n, m;
    cin >> n >> m;
    vector<string> d(n);
    for (int i = 0; i < n; i++)
        cin >> d[i];
    mf_graph<int> g(n * m + 2);
    for (int i = 0; i < n; i++) {
        for (int j = 0; j < m; j++) {
            int from = m * i + j + 1 + 1;
            if (d[i][j] == '.' && j + 1 < m && d[i][j + 1] == '.') {
                int to = m * i + j + 2 + 1;
                if ((i + j) % 2 == 0)
                    g.add_edge(from, to, 1);
                else
                    g.add_edge(to, from, 1);
            }

            if (d[i][j] == '.' && i + 1 < n && d[i + 1][j] == '.') {
                int to = m * (i + 1) + j + 1 + 1;
                if ((i + j) % 2 == 0)
                    g.add_edge(from, to, 1);
                else
                    g.add_edge(to, from, 1);
            }

            if (d[i][j] == '.') {
                if ((i + j) % 2 == 0)
                    g.add_edge(0, from, 1);
                else
                    g.add_edge(from, 1, 1);
            }
        }
    }

    vector<string> ans = d;

    cout << g.flow(0, 1) << '\n';
    int num = 0;
    for (int i = 0; i < n; i++) {
        for (int j = 0; j < m; j++) {
            int from = m * i + j + 1 + 1;
            if (d[i][j] == '.' && j + 1 < m && d[i][j + 1] == '.') {
                int to = m * i + j + 2 + 1;
                if (g.get_edge(num).flow == 1) {
                    ans[i][j] = '>';
                    ans[i][j + 1] = '<';
                }
                num++;
            }

            if (d[i][j] == '.' && i + 1 < n && d[i + 1][j] == '.') {
                int to = m * (i + 1) + j + 1 + 1;
                if (g.get_edge(num).flow == 1) {
                    ans[i][j] = 'v';
                    ans[i + 1][j] = '^';
                }
                num++;
            }

            if (d[i][j] == '.') {
                num++;
            }
        }
    }

    for (int i = 0; i < n; i++)
        cout << ans[i] << '\n';
}

int main() {
	ios_base::sync_with_stdio(0);
	cin.tie(0);
	cout.tie(0);
#if defined(_DEBUG)
	freopen("input.txt", "r", stdin);
	freopen("output.txt", "w", stdout);
#endif
	int q = 1;
	//cin >> q;
	for (; q > 0; q--) {
		solve();
		//cout << endl;
	}
}

Measured memory_bytes: 4856