use input_mcr::*;
use std::cmp::*;
use std::collections::HashMap;

use atcoder_maxflow::*;
use field::*;

fn main() {
    input! {
        h: usize,
        w: usize,
        field: [chars; h],
    }
    let field = Field::from_vec_vec(&field);
    let mut g = MaxFlowGraph::<i32>::new(h * w + 2);
    let mut mark = HashMap::new();
    for y in 0..h {
        for x in 0..w {
            if (x + y) % 2 == 0 {
                let p = Pos { x, y };
                if field[p] == '.' {
                    for (d, p2) in field.n4(p) {
                        if field[p2] == '.' {
                            g.add_edge(p.y * w + p.x, p2.y * w + p2.x, 1);
                            let cc = match d {
                                Dir::U => ('^', 'v'),
                                Dir::R => ('>', '<'),
                                Dir::D => ('v', '^'),
                                Dir::L => ('<', '>'),
                            };
                            mark.insert((p, p2), cc);
                        }
                    }
                }
            }
        }
    }
    for y in 0..h {
        for x in 0..w {
            if (x + y) % 2 == 0 {
                g.add_edge(h * w, y * w + x, 1);
            } else {
                g.add_edge(y * w + x, h * w + 1, 1);
            }
        }
    }
    let t = g.flow(h * w, h * w + 1, 10000);
    println!("{}", t);
    let mut res = field.clone();
    let edges = g.edges();
    for edge in &edges {
        if edge.flow != 0 {
            let p = Pos {
                x: edge.from % w,
                y: edge.from / w,
            };
            let p2 = Pos {
                x: edge.to % w,
                y: edge.to / w,
            };
            if let Some((c, c2)) = mark.get(&(p, p2)) {
                res[p] = *c;
                res[p2] = *c2;
            }
        }
    }
    let mut res_s = String::new();
    for y in 0..h {
        for x in 0..w {
            let p = Pos { x, y };
            res_s.push(res[p]);
        }
        res_s.push('\n');
    }
    print!("{}", res_s);
}
pub mod input_mcr {
    // ref: tanakh <https://qiita.com/tanakh/items/0ba42c7ca36cd29d0ac8>
    #[macro_export(local_inner_macros)]
    macro_rules! input {
        (source = $s:expr, $($r:tt)*) => {
            let mut parser = Parser::from_str($s);
            input_inner!{parser, $($r)*}
        };
        (parser = $parser:ident, $($r:tt)*) => {
            input_inner!{$parser, $($r)*}
        };
        (new_stdin_parser = $parser:ident, $($r:tt)*) => {
            let stdin = std::io::stdin();
            let reader = std::io::BufReader::new(stdin.lock());
            let mut $parser = Parser::new(reader);
            input_inner!{$parser, $($r)*}
        };
        ($($r:tt)*) => {
            input!{new_stdin_parser = parser, $($r)*}
        };
    }

    #[macro_export(local_inner_macros)]
    macro_rules! input_inner {
        ($parser:ident) => {};
        ($parser:ident, ) => {};
        ($parser:ident, $var:ident : $t:tt $($r:tt)*) => {
            let $var = read_value!($parser, $t);
            input_inner!{$parser $($r)*}
        };
    }

    #[macro_export(local_inner_macros)]
    macro_rules! read_value {
        ($parser:ident, ( $($t:tt),* )) => {
            ( $(read_value!($parser, $t)),* )
        };
        ($parser:ident, [ $t:tt ; $len:expr ]) => {
            (0..$len).map(|_| read_value!($parser, $t)).collect::<Vec<_>>()
        };
        ($parser:ident, chars) => {
            read_value!($parser, String).chars().collect::<Vec<char>>()
        };
        ($parser:ident, char_) => {
            read_value!($parser, String).chars().collect::<Vec<char>>()[0]
        };
        ($parser:ident, usize1) => {
            read_value!($parser, usize) - 1
        };
        ($parser:ident, line) => {
            $parser.next_line()
        };
        ($parser:ident, line_) => {
            $parser.next_line().chars().collect::<Vec<char>>()
        };
        ($parser:ident, $t:ty) => {
            $parser.next::<$t>().expect("Parse error")
        };
    }

    use std::collections::VecDeque;
    use std::io;
    use std::io::BufRead;
    use std::str;

    pub struct Parser<R> {
        pub reader: R,
        buf: VecDeque<u8>,
        parse_buf: Vec<u8>,
    }

    impl Parser<io::Empty> {
        pub fn from_str(s: &str) -> Parser<io::Empty> {
            Parser {
                reader: io::empty(),
                buf: VecDeque::from(s.as_bytes().to_vec()),
                parse_buf: vec![],
            }
        }
    }

    impl<R: BufRead> Parser<R> {
        pub fn new(reader: R) -> Parser<R> {
            Parser {
                reader: reader,
                buf: VecDeque::new(),
                parse_buf: vec![],
            }
        }
        pub fn update_buf(&mut self) {
            loop {
                let (len, complete) = {
                    let buf2 = self.reader.fill_buf().unwrap();
                    self.buf.extend(buf2.iter());
                    let len = buf2.len();
                    (len, buf2.last() < Some(&0x20))
                };
                self.reader.consume(len);
                if complete {
                    break;
                }
            }
        }
        pub fn next<T: str::FromStr>(&mut self) -> Result<T, T::Err> {
            loop {
                while let Some(c) = self.buf.pop_front() {
                    if c > 0x20 {
                        self.buf.push_front(c);
                        break;
                    }
                }
                self.parse_buf.clear();
                while let Some(c) = self.buf.pop_front() {
                    if c <= 0x20 {
                        self.buf.push_front(c);
                        break;
                    } else {
                        self.parse_buf.push(c);
                    }
                }
                if self.parse_buf.is_empty() {
                    self.update_buf();
                } else {
                    return unsafe { str::from_utf8_unchecked(&self.parse_buf) }.parse::<T>();
                }
            }
        }
        pub fn next_line(&mut self) -> String {
            loop {
                while let Some(c) = self.buf.pop_front() {
                    if c >= 0x20 {
                        self.buf.push_front(c);
                        break;
                    }
                }
                self.parse_buf.clear();
                while let Some(c) = self.buf.pop_front() {
                    if c < 0x20 {
                        self.buf.push_front(c);
                        break;
                    } else {
                        self.parse_buf.push(c);
                    }
                }
                if self.parse_buf.is_empty() {
                    self.update_buf();
                } else {
                    return unsafe { str::from_utf8_unchecked(&self.parse_buf) }.to_string();
                }
            }
        }
    }
}
pub mod atcoder_maxflow {
    use std::collections::VecDeque;
    use std::ops::{Add, AddAssign, Sub, SubAssign};

    #[derive(Clone, Copy)]
    struct GraphEdge<Cap> {
        to: usize,
        rev: usize,
        cap: Cap,
    }

    #[derive(Clone, Copy)]
    pub struct FlowEdge<Cap> {
        pub from: usize,
        pub to: usize,
        pub cap: Cap,
        pub flow: Cap,
    }

    pub struct MaxFlowGraph<Cap> {
        n: usize,
        pos: Vec<(usize, usize)>,
        g: Vec<Vec<GraphEdge<Cap>>>,
    }

    impl<
            Cap: Clone
                + Copy
                + PartialOrd<Cap>
                + From<i8>
                + Add<Output = Cap>
                + Sub<Output = Cap>
                + Sub<Output = Cap>
                + AddAssign<Cap>
                + SubAssign<Cap>,
        > MaxFlowGraph<Cap>
    {
        pub fn new(n: usize) -> MaxFlowGraph<Cap> {
            MaxFlowGraph::<Cap> {
                n,
                pos: vec![],
                g: vec![vec![]; n],
            }
        }

        pub fn add_edge(&mut self, from: usize, to: usize, cap: Cap) -> usize {
            assert!(from < self.n);
            assert!(to < self.n);
            assert!(Cap::from(0) <= cap);
            let m = self.pos.len();
            self.pos.push((from, self.g[from].len()));
            let e = GraphEdge {
                to,
                rev: self.g[to].len(),
                cap,
            };
            self.g[from].push(e);
            let e = GraphEdge {
                to: from,
                rev: self.g[from].len() - 1,
                cap: Cap::from(0),
            };
            self.g[to].push(e);
            m
        }

        pub fn get_edge(&self, i: usize) -> FlowEdge<Cap> {
            let m = self.pos.len();
            assert!(i < m);
            let e = self.g[self.pos[i].0][self.pos[i].1];
            let re = self.g[e.to][e.rev];
            FlowEdge {
                from: self.pos[i].0,
                to: e.to,
                cap: e.cap + re.cap,
                flow: re.cap,
            }
        }

        pub fn edges(&self) -> Vec<FlowEdge<Cap>> {
            let m = self.pos.len();
            let mut result = vec![];
            for i in 0..m {
                result.push(self.get_edge(i));
            }
            result
        }

        pub fn change_edge(&mut self, i: usize, new_cap: Cap, new_flow: Cap) {
            let m = self.pos.len();
            assert!(i < m);
            assert!(Cap::from(0) <= new_flow && new_flow <= new_cap);
            self.g[self.pos[i].0][self.pos[i].1].cap = new_cap - new_flow;
            let e = self.g[self.pos[i].0][self.pos[i].1];
            self.g[e.to][e.rev].cap = new_flow;
        }

        pub fn flow(&mut self, s: usize, t: usize, flow_limit: Cap) -> Cap {
            assert!(s < self.n);
            assert!(t < self.n);

            let mut level = vec![0; self.n];
            let mut iter = vec![0; self.n];
            let mut que = VecDeque::new();

            fn bfs<Cap: PartialOrd + From<i8>>(
                g: &Vec<Vec<GraphEdge<Cap>>>,
                que: &mut VecDeque<usize>,
                level: &mut Vec<i64>,
                iter: &mut Vec<usize>,
                s: usize,
                t: usize,
            ) {
                for x in level.iter_mut() {
                    *x = -1;
                }
                level[s] = 0;
                que.clear();
                que.push_back(s);
                while let Some(v) = que.pop_front() {
                    for e in &g[v] {
                        if e.cap == Cap::from(0) || level[e.to] >= 0 {
                            continue;
                        }
                        level[e.to] = level[v] + 1;
                        if e.to == t {
                            return;
                        }
                        que.push_back(e.to);
                    }
                }
            }

            fn dfs<
                Cap: Clone + Copy + Sub<Output = Cap> + From<i8> + PartialOrd + AddAssign + SubAssign,
            >(
                g: &mut Vec<Vec<GraphEdge<Cap>>>,
                level: &mut Vec<i64>,
                iter: &mut Vec<usize>,
                v: usize,
                up: Cap,
                s: usize,
            ) -> Cap {
                if v == s {
                    return up;
                }
                let mut res = Cap::from(0);
                let level_v = level[v];
                for i in iter[v]..g[v].len() {
                    iter[v] = i;
                    let e = g[v][i];
                    if level_v <= level[e.to] || g[e.to][e.rev].cap == Cap::from(0) {
                        continue;
                    }
                    let new_up = if up - res <= g[e.to][e.rev].cap {
                        up - res
                    } else {
                        g[e.to][e.rev].cap
                    };
                    let d = dfs(g, level, iter, e.to, new_up, s);
                    if d <= Cap::from(0) {
                        continue;
                    }
                    g[v][i].cap += d;
                    g[e.to][e.rev].cap -= d;
                    res += d;
                    if res == up {
                        break;
                    }
                }
                res
            }

            let mut flow = Cap::from(0);
            while flow < flow_limit {
                bfs(&mut self.g, &mut que, &mut level, &mut iter, s, t);
                if level[t] == -1 {
                    break;
                }
                for x in iter.iter_mut() {
                    *x = 0;
                }
                while flow < flow_limit {
                    let f = dfs(&mut self.g, &mut level, &mut iter, t, flow_limit - flow, s);
                    if f == Cap::from(0) {
                        break;
                    }
                    flow += f;
                }
            }
            flow
        }

        pub fn min_cut(&mut self, s: usize) {
            unimplemented!();
        }
    }
}
pub mod field {
    use std::iter::Iterator;
    use std::ops::{Index, IndexMut};

    #[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
    pub enum Dir {
        U,
        R,
        D,
        L,
    }

    pub const DIRS: [Dir; 4] = [Dir::U, Dir::R, Dir::D, Dir::L];

    #[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Default, Hash)]
    pub struct Pos {
        pub x: usize,
        pub y: usize,
    }

    #[derive(Debug, Clone, PartialEq, Eq, PartialOrd, Ord, Default, Hash)]
    pub struct Field<T> {
        h: usize,
        w: usize,
        field: Vec<T>,
    }

    pub struct N4 {
        i: usize,
        x: usize,
        y: usize,
        h: usize,
        w: usize,
    }

    impl Iterator for N4 {
        type Item = (Dir, Pos);
        fn next(&mut self) -> Option<(Dir, Pos)> {
            let dx = [0, 1, 0, -1];
            let dy = [-1, 0, 1, 0];
            while self.i < 4 {
                let nx = self.x as i64 + dx[self.i];
                let ny = self.y as i64 + dy[self.i];
                if 0 <= nx && nx < self.w as i64 && 0 <= ny && ny < self.h as i64 {
                    self.i += 1;
                    return Some((
                        DIRS[self.i - 1],
                        Pos {
                            x: nx as usize,
                            y: ny as usize,
                        },
                    ));
                }
                self.i += 1;
            }
            None
        }
    }

    pub struct Nexts<'a, T> {
        field: &'a Field<T>,
        pos: Pos,
        dir: Dir,
    }

    impl<'a, T: Clone + Copy + Default> Iterator for Nexts<'a, T> {
        type Item = Pos;
        fn next(&mut self) -> Option<Pos> {
            let pos2 = self.field.next(self.pos, self.dir);
            if let Some(pos2) = pos2 {
                self.pos = pos2;
                Some(pos2)
            } else {
                None
            }
        }
    }

    impl<T: Clone + Copy + Default> Field<T> {
        pub fn new(h: usize, w: usize, default: T) -> Field<T> {
            Field::<T> {
                h,
                w,
                field: vec![default; h * w],
            }
        }
        pub fn from_vec_vec(xss: &Vec<Vec<T>>) -> Field<T> {
            let h = xss.len();
            let w = xss[0].len();
            let mut field = vec![];
            for y in 0..h {
                for x in 0..w {
                    field.push(xss[y][x]);
                }
            }
            Field::<T> { h, w, field }
        }
        pub fn n4(&self, pos: Pos) -> N4 {
            N4 {
                i: 0,
                x: pos.x,
                y: pos.y,
                h: self.h,
                w: self.w,
            }
        }
        pub fn next(&self, pos: Pos, dir: Dir) -> Option<Pos> {
            match dir {
                Dir::U => {
                    if pos.y > 0 {
                        return Some(Pos {
                            x: pos.x,
                            y: pos.y - 1,
                        });
                    }
                }
                Dir::R => {
                    if pos.x + 1 < self.w {
                        return Some(Pos {
                            x: pos.x + 1,
                            y: pos.y,
                        });
                    }
                }
                Dir::D => {
                    if pos.y + 1 < self.h {
                        return Some(Pos {
                            x: pos.x,
                            y: pos.y + 1,
                        });
                    }
                }
                Dir::L => {
                    if pos.x > 0 {
                        return Some(Pos {
                            x: pos.x - 1,
                            y: pos.y,
                        });
                    }
                }
            }
            None
        }
        pub fn nexts<'a>(&'a self, pos: Pos, dir: Dir) -> Nexts<'a, T> {
            Nexts {
                field: self,
                pos,
                dir,
            }
        }
    }

    impl<T: Clone + Copy + Default> Index<Pos> for Field<T> {
        type Output = T;
        fn index(&self, pos: Pos) -> &T {
            &self.field[pos.y * self.w + pos.x]
        }
    }

    impl<T: Clone + Copy + Default> IndexMut<Pos> for Field<T> {
        fn index_mut(&mut self, pos: Pos) -> &mut T {
            &mut self.field[pos.y * self.w + pos.x]
        }
    }
}


Measured memory_bytes: 7652