#include <bits/stdc++.h>
using namespace std;
using LL = long long int;
#define incII(i, l, r) for(LL i = (l)    ; i <= (r); i++)
#define incIX(i, l, r) for(LL i = (l)    ; i <  (r); i++)
#define incXI(i, l, r) for(LL i = (l) + 1; i <= (r); i++)
#define incXX(i, l, r) for(LL i = (l) + 1; i <  (r); i++)
#define decII(i, l, r) for(LL i = (r)    ; i >= (l); i--)
#define decIX(i, l, r) for(LL i = (r) - 1; i >= (l); i--)
#define decXI(i, l, r) for(LL i = (r)    ; i >  (l); i--)
#define decXX(i, l, r) for(LL i = (r) - 1; i >  (l); i--)
#define inc(i, n)  incIX(i, 0, n)
#define dec(i, n)  decIX(i, 0, n)
#define inc1(i, n) incII(i, 1, n)
#define dec1(i, n) decII(i, 1, n)
auto inII = [](auto x, auto l, auto r) { return (l <= x && x <= r); };
auto inIX = [](auto x, auto l, auto r) { return (l <= x && x <  r); };
auto inXI = [](auto x, auto l, auto r) { return (l <  x && x <= r); };
auto inXX = [](auto x, auto l, auto r) { return (l <  x && x <  r); };
auto setmin   = [](auto & a, auto b) { return (b <  a ? a = b, true : false); };
auto setmax   = [](auto & a, auto b) { return (b >  a ? a = b, true : false); };
auto setmineq = [](auto & a, auto b) { return (b <= a ? a = b, true : false); };
auto setmaxeq = [](auto & a, auto b) { return (b >= a ? a = b, true : false); };
#define PB push_back
#define EB emplace_back
#define MP make_pair
#define MT make_tuple
#define FI first
#define SE second
#define FR front()
#define BA back()
#define ALL(c) c.begin(), c.end()
#define RALL(c) c.rbegin(), c.rend()
#define RV(c) reverse(ALL(c))
#define SC static_cast
#define SI(c) SC<int>(c.size())
#define SL(c) SC<LL >(c.size())
#define RF(e, c) for(auto & e: c)
#define SF(c, ...) for(auto & [__VA_ARGS__]: c)
#define until(e) while(! (e))
#define if_not(e) if(! (e))
#define ef else if
#define UR assert(false)
auto * IS = & cin;
auto * OS = & cout;
array<string, 3> SEQ = { "", " ", "" };
// input elements (as a tuple)
template<typename U, int I> void in_([[maybe_unused]] U & t) { }
template<typename U, int I, typename A, typename ... B> void in_(U & t) { (* IS) >> get<I>(t); in_<U, I + 1, B ...>(t); }
template<typename ... T> auto in() { tuple<T ...> t; in_<tuple<T ...>, 0, T ...>(t); return t; }
// input an array
template<typename T, int N> auto ain() { array<T, N> a; inc(i, N) { (* IS) >> a[i]; } return a; }
// input a (multi-dimensional) vector
template<typename T> T vin() { T v; (* IS) >> v; return v; }
template<typename T, typename N, typename ... M> auto vin(N n, M ... m) {
	vector<decltype(vin<T, M ...>(m ...))> v(n); inc(i, n) { v[i] = vin<T, M ...>(m ...); } return v;
}
// input multi-column (as a tuple of vector)
template<typename U, int I> void colin_([[maybe_unused]] U & t) { }
template<typename U, int I, typename A, typename ... B> void colin_(U & t) {
	A a; (* IS) >> a; get<I>(t).push_back(a); colin_<U, I + 1, B ...>(t);
}
template<typename ... T> auto colin(int n) {
	tuple<vector<T> ...> t; inc(i, n) { colin_<tuple<vector<T> ...>, 0, T ...>(t); } return t;
}
// output elements
void out_([[maybe_unused]] string s) { }
template<typename A> void out_([[maybe_unused]] string s, A && a) { (* OS) << a; }
template<typename A, typename ... B> void out_(string s, A && a, B && ... b) { (* OS) << a << s; out_(s, b ...); }
auto outF = [](auto x, auto y, auto z, auto ... a) { (* OS) << x; out_(y, a ...); (* OS) << z << flush; };
auto out  = [](auto ... a) { outF("", " " , "\n", a ...); };
auto outS = [](auto ... a) { outF("", " " , " " , a ...); };
auto outL = [](auto ... a) { outF("", "\n", "\n", a ...); };
auto outN = [](auto ... a) { outF("", ""  , ""  , a ...); };
// output a (multi-dimensional) vector
template<typename T> ostream & operator<<(ostream & os, vector<T> const & v) {
	os << SEQ[0]; inc(i, SI(v)) { os << (i == 0 ? "" : SEQ[1]) << v[i]; } return (os << SEQ[2]);
}
template<typename T> void vout_(T && v) { (* OS) << v; }
template<typename T, typename A, typename ... B> void vout_(T && v, A a, B ... b) {
	inc(i, SI(v)) { (* OS) << (i == 0 ? "" : a); vout_(v[i], b ...); }
}
template<typename T, typename A, typename ... B> void vout(T && v, A a, B ... b) {
	vout_(v, b ...); (* OS) << a << flush;
}

// ---- ----

#include <atcoder/all>
using namespace atcoder;

auto dd = [](int h, int w, int i, int j, int k) -> tuple<bool, int, int> {
	vector<int> di = { +1,  0, -1,  0, +1, +1, -1, -1, 0 };
	vector<int> dj = {  0, +1,  0, -1, +1, -1, +1, -1, 0 };
	int ii = i + di.at(k);
	int jj = j + dj.at(k);
	return { inIX(ii, 0, h) && inIX(jj, 0, w), ii, jj };
};

int main() {
	auto [h, w] = in<int, int>();
	auto s = vin<string>(h);
	
	auto id = [&](int i, int j) { return w * i + j; };
	auto pos = [&](int x) -> pair<int, int> { return { x / w, x % w }; };
	
	mf_graph<int> g(h * w + 2);
	int S = h * w, T = S + 1;
	inc(i, h) {
	inc(j, w) {
		if_not(s[i][j] == '.') { continue; }
		if((i + j) % 2 == 0) {
			g.add_edge(S, id(i, j), 1);
		} else {
			g.add_edge(id(i, j), T, 1);
		}
		inc(k, 4) {
			auto [f, ii, jj] = dd(h, w, i, j, k);
			if_not(f && s[ii][jj] == '.') { continue; }
			if((i + j) % 2 == 0) {
				g.add_edge(id(i, j), id(ii, jj), 1);
			} else {
				g.add_edge(id(ii, jj), id(i, j), 1);
			}
		}
	}
	}
	
	out(g.flow(S, T));
	auto ans = g.edges();
	SF(ans, a, b, c_, f) {
		if(a == S || b == T || f == 0) { continue; }
		auto [ai, aj] = pos(a);
		auto [bi, bj] = pos(b);
		if(ai == bi) {
			if_not(aj <= bj) { swap(aj, bj); }
			s[ai][aj] = '>';
			s[bi][bj] = '<';
		}
		if(aj == bj) {
			if_not(ai <= bi) { swap(ai, bi); }
			s[ai][aj] = 'v';
			s[bi][bj] = '^';
		}
	}
	SEQ[1] = "\n";
	out(s);
}


Measured memory_bytes: 6976