#line 2 "/Users/kaage/Desktop/ProgrammingWorkspace/library/other/template.hpp"
#define _CRT_SECURE_NO_WARNINGS
#pragma target("avx2")
#pragma optimize("O3")
#pragma optimize("unroll-loops")
#include <algorithm>
#include <bitset>
#include <cassert>
#include <cfloat>
#include <climits>
#include <cmath>
#include <complex>
#include <ctime>
#include <deque>
#include <fstream>
#include <functional>
#include <iomanip>
#include <iostream>
#include <iterator>
#include <list>
#include <map>
#include <memory>
#include <queue>
#include <random>
#include <set>
#include <stack>
#include <string>
#include <string.h>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include <vector>
#define rep(i,n) for(int i=0;i<(n);i++)
#define REP(i,n) for(int i=1;i<=(n);i++)
#define all(V) V.begin(),V.end()
typedef unsigned int uint;
typedef long long lint;
typedef unsigned long long ulint;
typedef std::pair<int, int> P;
typedef std::pair<lint, lint> LP;
constexpr int INF = INT_MAX/2;
constexpr lint LINF = LLONG_MAX/2;
constexpr double eps = DBL_EPSILON;
constexpr double PI=3.141592653589793238462643383279;
template<class T>
class prique :public std::priority_queue<T, std::vector<T>, std::greater<T>> {};
template <class T, class U>
inline bool chmax(T& lhs, const U& rhs) {
	if (lhs < rhs) {
		lhs = rhs;
		return 1;
	}
	return 0;
}
template <class T, class U>
inline bool chmin(T& lhs, const U& rhs) {
	if (lhs > rhs) {
		lhs = rhs;
		return 1;
	}
	return 0;
}
inline lint gcd(lint a, lint b) {
	while (b) {
		lint c = a;
		a = b; b = c % b;
	}
	return a;
}
inline lint lcm(lint a, lint b) {
	return a / gcd(a, b) * b;
}
bool isprime(lint n) {
	if (n == 1)return false;
	for (int i = 2; i * i <= n; i++) {
		if (n % i == 0)return false;
	}
	return true;
}
template<typename T>
T mypow(T a, lint b) {
	T res(1);
	while(b){
		if(b&1)res*=a;
		a*=a;
		b>>=1;
	}
	return res;
}
lint modpow(lint a, lint b, lint m) {
	lint res(1);
	while(b){
		if(b&1){
			res*=a;res%=m;
		}
		a*=a;a%=m;
		b>>=1;
	}
	return res;
}
template<typename T>
void printArray(std::vector<T>& vec) {
	rep(i, vec.size()){
		std::cout << vec[i];
		std::cout<<(i==(int)vec.size()-1?"\n":" ");
	}
}
template<typename T>
void printArray(T l, T r) {
	T rprev = std::prev(r);
	for (T i = l; i != rprev; i++) {
		std::cout << *i << " ";
	}
	std::cout << *rprev << std::endl;
}
LP extGcd(lint a,lint b) {
	if(b==0)return {1,0};
	LP s=extGcd(b,a%b);
	std::swap(s.first,s.second);
	s.second-=a/b*s.first;
	return s;
}
LP ChineseRem(const lint& b1,const lint& m1,const lint& b2,const lint& m2) {
	lint p=extGcd(m1,m2).first;
	lint tmp=(b2-b1)*p%m2;
	lint r=(b1+m1*tmp+m1*m2)%(m1*m2);
	return std::make_pair(r,m1*m2);
}
template<typename F>
inline constexpr decltype(auto) lambda_fix(F&& f){
	return [f=std::forward<F>(f)](auto&&... args){
		return f(f,std::forward<decltype(args)>(args)...);
	};
}
#line 3 "/Users/kaage/Desktop/ProgrammingWorkspace/library/graph/FordFulkerson.hpp"
class FordFulkerson{
	class edge{
	public:
		int to;
		lint cap;
		int rev,id;
		bool isrev;
	};
	int n,idx=0;
	std::vector<std::vector<edge>> vec;
	std::vector<bool> used;
	lint dfs(int v,int t,lint f){
		if(v==t)return f;
		used[v]=true;
		for(edge& e:vec[v]){
			if(!used[e.to]&&e.cap>0){
				lint d=dfs(e.to,t,std::min(f,e.cap));
				if(d){
					e.cap-=d;
					vec[e.to][e.rev].cap+=d;
					return d;
				}
			}
		}
		return 0;
	}
public:
	FordFulkerson(int n):n(n){
		vec.resize(n);
		used.resize(n);
	}
	void add_edge(int from,int to,lint cap){
		vec[from].push_back({to,cap,(int)vec[to].size(),idx,false});
		vec[to].push_back({from,0,(int)vec[from].size()-1,idx++,true});
	}
	lint max_flow(int s,int t){
		lint res=0;
		while(true){
			used.assign(n,false);
			lint f=dfs(s,t,LINF);
			if(!f)return res;
			res+=f;
		}
	}
	std::vector<lint> restore(){
		std::vector<lint> res(idx);
		rep(i,n){
			for(const auto& j:vec[i]){
				if(j.isrev)res[j.id]=j.cap;
			}
		}
		return res;
	}
};
#line 3 "main.cpp"
int n,m;
char s[110][110];
int dx[]={0,1,0,-1};
int dy[]={1,0,-1,0};
std::vector<P> evec;
int main(){
	std::cin>>n>>m;
	FordFulkerson flow(n*m+n*(m-1)+(n-1)*m+2);
	rep(i,n){
		rep(j,m)std::cin>>s[i][j];
	}
	rep(i,n){
		rep(j,m){
			if(s[i][j]=='#')continue;
			if((i+j)%2){
				flow.add_edge(0,i*m+j+1,1);
				evec.emplace_back(0,i*m+j+1);
				rep(k,4){
					int ni=i+dx[k],nj=j+dy[k];
					if(ni<0||n<=ni||nj<0||m<=nj||s[ni][nj]=='#')continue;
					flow.add_edge(i*m+j+1,ni*m+nj+1,1);
					evec.emplace_back(i*m+j+1,ni*m+nj+1);
				}
			}
			else{
				flow.add_edge(i*m+j+1,n*m+1,1);
				evec.emplace_back(i*m+j+1,n*m+1);
			}
		}
	}
	std::cout<<flow.max_flow(0,n*m+1)<<std::endl;
	std::vector<lint> vec=flow.restore();
	rep(i,evec.size()){
		if(vec[i]&&evec[i].first!=0&&evec[i].second!=n*m+1){
			evec[i].first--;evec[i].second--;
			if(evec[i].first>evec[i].second)std::swap(evec[i].first,evec[i].second);
			if(evec[i].first/m==evec[i].second/m){
				s[evec[i].first/m][evec[i].first%m]='>';
				s[evec[i].second/m][evec[i].second%m]='<';
			}
			else{
				s[evec[i].first/m][evec[i].first%m]='v';
				s[evec[i].second/m][evec[i].second%m]='^';
			}
		}
	}
	rep(i,n){
		rep(j,m)std::cout<<s[i][j];
		std::cout<<std::endl;
	}
	return 0;
}

Measured memory_bytes: 7632