using System;
using System.Collections.Generic;
using System.Linq;
using System.IO;
using System.Threading;
using System.Runtime.CompilerServices;
using System.Text;
using System.Diagnostics;
using System.Numerics;
using static System.Console;
using static System.Convert;
using static System.Math;
using static Template;
using SC = Scanner;

public partial class Solver
{
    int N, M;
    public void Solve()
    {
        sc.Make(out N, out M);
        var G = sc.Grid(N);
        var f = new Dinic(N * M + 2);

        for (int i = 0; i < N; i++)
            for (int j = 0; j < M; j++)
            {
                if (G[i][j] == '#') continue;
                if ((i + j) % 2 == 1)
                {
                    f.AddEdge(Id(i, j), N * M + 1, 1);
                    continue;
                }
                f.AddEdge(N * M, Id(i, j), 1);
                for (int k = 0; k < gh.Length; k++)
                {
                    int h = gh[k] + i, w = gw[k] + j;
                    if (!Inside(h, w, N, M) || G[h][w] == '#') continue;
                    f.AddEdge(Id(i, j), Id(h, w), 1);

                }
            }
        var res = f.Execute(N * M, N * M + 1);
        foreach (var e in f.edges)
        {
            if ((e.idx & 1) == 0 || e.cap == 0 || e.fr >= N * M || e.to >= N * M) continue;
            int h1 = e.fr / M, w1 = e.fr % M, h2 = e.to / M, w2 = e.to % M;
            if (h1 > h2 || w1 > w2)
            {
                swap(ref h1, ref h2); swap(ref w1, ref w2);
            }
            if (h1 != h2)
            {
                G[h1][w1] = 'v';
                G[h2][w2] = '^';
            }
            else
            {
                G[h1][w1] = '>';
                G[h2][w2] = '<';
            }
        }
        Console.WriteLine(res);
        Console.WriteLine(G.Select(v => new string(v)).Concat("\n"));
    }
    public int Id(int h, int w) => h * M + w;
    int[] gh = new[] { 0, 0, 1, -1 }, gw = new[] { 1, -1, 0, 0 };
    public static bool Inside(int h, int w, int H, int W)
        => 0 <= h && h < H && 0 <= w && w < W;
}

class Dinic
{
    public List<Edge> edges;
    List<int>[] G;
    int[] mincost, iter;
    public Dinic(int V)
    {
        iter = new int[V];
        mincost = new int[V];
        edges = new List<Edge>();
        G = Create(V, () => new List<int>());
    }
    public void AddEdge(int from, int to, int cap)
    {
        int edgeIndex = edges.Count;
        G[from].Add(edgeIndex);
        edges.Add(new Edge(from, to, cap, edgeIndex));
        G[to].Add(edgeIndex + 1);
        edges.Add(new Edge(to, from, 0, edgeIndex + 1));
    }
    bool ExistAugmentingPath(int s, int t)
    {
        for (int i = 0; i < mincost.Length; i++) mincost[i] = -1;
        var Q = new Queue<int>();
        mincost[s] = 0;
        Q.Enqueue(s);
        while (Q.Any() && mincost[t] == -1)
        {
            var p = Q.Dequeue();
            foreach (var eidx in G[p])
            {
                var e = edges[eidx];
                if (e.cap > 0 && mincost[e.to] == -1)
                {
                    mincost[e.to] = mincost[p] + 1;
                    Q.Enqueue(e.to);
                }
            }
        }
        return mincost[t] != -1;
    }
    int FindBottleneck(int idx, int t, int flow)
    {
        if (idx == t) return flow;
        for (; iter[idx] < G[idx].Count; iter[idx]++)
        {
            var eg = edges[G[idx][iter[idx]]];
            if (eg.cap > 0 && mincost[idx] < mincost[eg.to])
            {
                var d = FindBottleneck(eg.to, t, Min(flow, eg.cap));
                if (d > 0)
                {
                    eg.cap -= d;
                    edges[eg.idx ^ 1].cap += d;
                    return d;
                }
            }
        }
        return 0;
    }
    public int Execute(int s, int t, int f = int.MaxValue)
    {
        int flow = 0;
        while (f > 0 && ExistAugmentingPath(s, t))
        {
            Array.Clear(iter, 0, iter.Length);
            int df = 0;
            while ((df = FindBottleneck(s, t, f)) > 0) { flow += df; f -= df; }
        }
        return flow;
    }
    public class Edge
    {
        public int fr, to, idx, cap;
        public Edge(int f, int t, int c, int i)
        {
            fr = f; to = t; cap = c; idx = i;
        }
    }
}

#region Template
public partial class Solver
{
    public SC sc = new SC();
    static void Main(string[] args)
    {
        Console.SetOut(new StreamWriter(Console.OpenStandardOutput()) { AutoFlush = false });
        var sol = new Solver();
        int testcase = 1;
        //testcase = sol.sc.Int;
        //var th = new Thread(sol.Solve, 1 << 26);th.Start();th.Join();
        while (testcase-- > 0)
            sol.Solve();
        Console.Out.Flush();
    }
}
public static class Template
{
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public static bool chmin<T>(ref T a, T b) where T : IComparable<T> { if (a.CompareTo(b) > 0) { a = b; return true; } return false; }
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public static bool chmax<T>(ref T a, T b) where T : IComparable<T> { if (a.CompareTo(b) < 0) { a = b; return true; } return false; }
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public static void swap<T>(ref T a, ref T b) { var t = b; b = a; a = t; }
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public static void swap<T>(this IList<T> A, int i, int j) { var t = A[i]; A[i] = A[j]; A[j] = t; }
    public static T[] Create<T>(int n, Func<T> f) { var rt = new T[n]; for (var i = 0; i < rt.Length; ++i) rt[i] = f(); return rt; }
    public static T[] Create<T>(int n, Func<int, T> f) { var rt = new T[n]; for (var i = 0; i < rt.Length; ++i) rt[i] = f(i); return rt; }
    public static void Out<T>(this IList<T> A, out T a) => a = A[0];
    public static void Out<T>(this IList<T> A, out T a, out T b) { a = A[0]; b = A[1]; }
    public static void Out<T>(this IList<T> A, out T a, out T b, out T c) { A.Out(out a, out b); c = A[2]; }
    public static void Out<T>(this IList<T> A, out T a, out T b, out T c, out T d) { A.Out(out a, out b, out c); d = A[3]; }
    public static string Concat<T>(this IEnumerable<T> A, string sp) => string.Join(sp, A);
    public static char ToChar(this int s, char begin = '0') => (char)(s + begin);
    public static IEnumerable<T> Shuffle<T>(this IEnumerable<T> A) => A.OrderBy(v => Guid.NewGuid());
    public static int CompareTo<T>(this T[] A, T[] B, Comparison<T> cmp = null) { cmp = cmp ?? Comparer<T>.Default.Compare; for (var i = 0; i < Min(A.Length, B.Length); i++) { int c = cmp(A[i], B[i]); if (c > 0) return 1; else if (c < 0) return -1; } if (A.Length == B.Length) return 0; if (A.Length > B.Length) return 1; else return -1; }
    public static string ToStr<T>(this T[][] A) => A.Select(a => a.Concat(" ")).Concat("\n");
    public static int ArgMax<T>(this IList<T> A, Comparison<T> cmp = null) { cmp = cmp ?? Comparer<T>.Default.Compare; T max = A[0]; int rt = 0; for (int i = 1; i < A.Count; i++) if (cmp(max, A[i]) < 0) { max = A[i]; rt = i; } return rt; }
    public static T PopBack<T>(this List<T> A) { var v = A[A.Count - 1]; A.RemoveAt(A.Count - 1); return v; }
    public static void Fail<T>(T s) { Console.WriteLine(s); Console.Out.Close(); Environment.Exit(0); }
}
public class Scanner
{
    public string Str => Console.ReadLine().Trim();
    public int Int => int.Parse(Str);
    public long Long => long.Parse(Str);
    public double Double => double.Parse(Str);
    public int[] ArrInt => Str.Split(' ').Select(int.Parse).ToArray();
    public long[] ArrLong => Str.Split(' ').Select(long.Parse).ToArray();
    public char[][] Grid(int n) => Create(n, () => Str.ToCharArray());
    public int[] ArrInt1D(int n) => Create(n, () => Int);
    public long[] ArrLong1D(int n) => Create(n, () => Long);
    public int[][] ArrInt2D(int n) => Create(n, () => ArrInt);
    public long[][] ArrLong2D(int n) => Create(n, () => ArrLong);
    private Queue<string> q = new Queue<string>();
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public T Next<T>() { if (q.Count == 0) foreach (var item in Str.Split(' ')) q.Enqueue(item); return (T)Convert.ChangeType(q.Dequeue(), typeof(T)); }
    public void Make<T1>(out T1 v1) => v1 = Next<T1>();
    public void Make<T1, T2>(out T1 v1, out T2 v2) { v1 = Next<T1>(); v2 = Next<T2>(); }
    public void Make<T1, T2, T3>(out T1 v1, out T2 v2, out T3 v3) { Make(out v1, out v2); v3 = Next<T3>(); }
    public void Make<T1, T2, T3, T4>(out T1 v1, out T2 v2, out T3 v3, out T4 v4) { Make(out v1, out v2, out v3); v4 = Next<T4>(); }
    public void Make<T1, T2, T3, T4, T5>(out T1 v1, out T2 v2, out T3 v3, out T4 v4, out T5 v5) { Make(out v1, out v2, out v3, out v4); v5 = Next<T5>(); }
    public void Make<T1, T2, T3, T4, T5, T6>(out T1 v1, out T2 v2, out T3 v3, out T4 v4, out T5 v5, out T6 v6) { Make(out v1, out v2, out v3, out v4, out v5); v6 = Next<T6>(); }
    public void Make<T1, T2, T3, T4, T5, T6, T7>(out T1 v1, out T2 v2, out T3 v3, out T4 v4, out T5 v5, out T6 v6, out T7 v7) { Make(out v1, out v2, out v3, out v4, out v5, out v6); v7 = Next<T7>(); }
    public (T1, T2) Make<T1, T2>() { Make(out T1 v1, out T2 v2); return (v1, v2); }
    public (T1, T2, T3) Make<T1, T2, T3>() { Make(out T1 v1, out T2 v2, out T3 v3); return (v1, v2, v3); }
    public (T1, T2, T3, T4) Make<T1, T2, T3, T4>() { Make(out T1 v1, out T2 v2, out T3 v3, out T4 v4); return (v1, v2, v3, v4); }
}

#endregion

Measured memory_bytes: 42708