// Create your own template by modifying this file!
#include <string>
#include <vector>
#include <climits>
#include <cstring>
#include <map>
#include <queue>
#include <algorithm>
#include <cmath>
#include <cstdio>
#include <iostream>
#include <set>
#include <unordered_set>
#include <unordered_map>
#include <cassert>
#include <deque>
#include <stack>
#include <functional>
#define SZ(X) ((int)(X).size())
#define ALL(X) (X).begin(), (X).end()
#define REP(I, N) for (int I = 0; I < (N); ++I)
#define REPP(I, A, B) for (int I = (A); I < (B); ++I)
#define FOR(I, A, B) for (int I = (A); I <= (B); ++I)
#define FORS(I, S) for (int I = 0; S[I]; ++I)
#define RS(X) scanf("%s", (X))
#define SORT_UNIQUE(c) (sort(c.begin(),c.end()), c.resize(distance(c.begin(),unique(c.begin(),c.end()))))
#define GET_POS(c,x) (lower_bound(c.begin(),c.end(),x)-c.begin())
#define CASET int ___T; scanf("%d", &___T); for(int cs=1;cs<=___T;cs++)
#define MP make_pair
#define PB emplace_back
#define MS0(X) memset((X), 0, sizeof((X)))
#define MS1(X) memset((X), -1, sizeof((X)))
#define LEN(X) strlen(X)
#define F first
#define S second
using namespace std;
typedef long long LL;
typedef unsigned long long ULL;
typedef long double LD;
typedef pair<int,int> PII;
typedef vector<int> VI;
typedef vector<LL> VL;
typedef vector<PII> VPII;
typedef pair<LL,LL> PLL;
typedef vector<PLL> VPLL;
template<class T> void _R(T &x) { cin >> x;  }
void _R(int &x) { scanf("%d", &x);  }
void _R(int64_t &x) { scanf("%lld", &x);  }
void _R(double &x) { scanf("%lf", &x);  }
void _R(char &x) { scanf(" %c", &x);  }
void _R(char *x) { scanf("%s", x);  }
void R() {}
template<class T, class... U> void R(T &head, U &... tail) { _R(head); R(tail...);  }
template<class T> void _W(const T &x) { cout << x;  }
void _W(const int &x) { printf("%d", x);  }
void _W(const int64_t &x) { printf("%lld", x);  }
void _W(const double &x) { printf("%.16f", x);  }
void _W(const char &x) { putchar(x);  }
void _W(const char *x) { printf("%s", x);  }
template<class T,class U> void _W(const pair<T,U> &x) {_W(x.F); putchar(' '); _W(x.S);}
template<class T> void _W(const vector<T> &x) { for (auto i = x.begin(); i != x.end(); _W(*i++)) if (i != x.cbegin()) putchar(' ');  }
void W() {}
template<class T, class... U> void W(const T &head, const U &... tail) { _W(head); putchar(sizeof...(tail) ? ' ' : '\n'); W(tail...);  }
#ifdef DEBUG
 #define debug(...) {printf("[DEBUG] ");W(__VA_ARGS__);}
#else
 #define debug(...)
#endif
int MOD = 1e9+7;
void ADD(LL& x,LL v){x=(x+v)%MOD;if(x<0)x+=MOD;}
/*}}}*/
const int SIZE = 1<<20;
template<class T> void MIN(T& a, const T& b) { a = min(a, b); }
template<class T> void MAX(T& a, const T& b) { a = max(a, b); }

#include <atcoder/all>
#define MULTITEST 0

using namespace atcoder;

char S[105][105];

void solve() {
    int N, M;
    R(N, M);

    REP(i, N) {
        R(S[i]);
    }

    mf_graph<int> graph(N*M+2);
    int s = N * M, t = s + 1;
    REP(i, N) {
        REP(j, M) {
            if (S[i][j] == '.') {
                if ((i + j) % 2) {
                    graph.add_edge(s, M*i+j, 1);
                    if (j+1 < M && S[i][j+1] == '.') {
                        graph.add_edge(M*i+j, M*i+j+1, 1);
                    }
                    if (j-1 < M && S[i][j-1] == '.') {
                        graph.add_edge(M*i+j, M*i+j-1, 1);
                    }
                    if (i+1 < N && S[i+1][j] == '.') {
                        graph.add_edge(M*i+j, M*(i+1)+j, 1);
                    }
                    if (i-1 < N && S[i-1][j] == '.') {
                        graph.add_edge(M*i+j, M*(i-1)+j, 1);
                    }
                } else {
                    graph.add_edge(M*i+j, t, 1);
                }
            }
        }
    }

    W(graph.flow(s, t));

    for (auto &edge : graph.edges()) {
        if (edge.from != s && edge.to != t && edge.flow > 0) {
            int i1 = edge.from / M, j1 = edge.from % M;
            int i2 = edge.to / M, j2 = edge.to % M;
            if (i1 == i2) {
                S[i1][min(j1, j2)] = '>';
                S[i2][max(j1, j2)] = '<';
            } else {
                S[min(i1, i2)][j1] = 'v';
                S[max(i1, i2)][j2] = '^';
            }
        }
    }
    REP(i, N) {
        W(S[i]);
    }
}

int main() {
#if MULTITEST    
    CASET{
        solve();
    }
#else
    solve();
#endif
    return 0;
}


Measured memory_bytes: 5200