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/*
This is quite inefficient, but it still gives the right answer in less
than a minute (25 seconds on my old laptop).
*/
#include <iostream>
#include <algorithm>
#include <string>
#include <string_view>
#include <vector>
using namespace std;
enum Direction { U = 0, D, R, L };
Direction all_directions[] = {
Direction::U, Direction::D, Direction::R, Direction::L,
};
pair<int, int> step(pair<int, int> p, Direction d) {
auto [i, j] = p;
switch (d) {
case Direction::U:
return make_pair(i-1, j);
case Direction::D:
return make_pair(i+1, j);
case Direction::R:
return make_pair(i, j+1);
case Direction::L:
return make_pair(i, j-1);
}
return make_pair(-999,-999);
}
Direction turn(Direction d) {
switch (d) {
case Direction::U:
return Direction::R;
case Direction::D:
return Direction::L;
case Direction::R:
return Direction::D;
case Direction::L:
return Direction::U;
}
return Direction::U;
}
class Board {
public:
const char out_of_bound = '$';
int M, N;
Board(vector<string> &lines) {
N = lines.size();
M = 0;
for (string l : lines)
M = max(M, (int)l.size());
cells = new char[M * N];
visited = new int[M * N];
for (int i = 0; i < N; i++) {
for (int j = 0; j < M; j++) {
cells[N*i + j] = j < (int)lines[i].size() ?
lines[i][j] : out_of_bound;
visited[N*i + j] = 0;
}
}
}
~Board() {
delete []cells;
delete []visited;
}
char operator[](pair<int, int> p) {
int c = coord(p);
return c == -1 ? out_of_bound : cells[c];
}
bool is_visited(pair<int, int> p, Direction d) {
return get_vmask(p) & (1 << d);
}
void set_visited(pair<int, int> p, Direction d) {
toggle_vmask(p, d);
}
void clear_visited() {
for (int i = 0; i < N; i++)
for (int j = 0; j < M; j++)
set_vmask(make_pair(i, j), 0);
}
bool is_obstruction(pair<int, int> p) {
return (*this)[p] == '#';
}
void set_obstruction(pair<int, int> p) {
set_cell(p, '#');
}
void set_clean(pair<int, int> p) {
set_cell(p, '.');
}
private:
char *cells;
int *visited;
int coord(pair<int, int> p) {
auto [i, j] = p;
return i >= N || i < 0 || j >= M || j < 0 ? -1 : N*i + j;
}
void set_cell(pair<int, int> p, char c) {
int i = coord(p);
cells[i] = c;
}
int get_vmask(pair<int, int> p) {
int i = coord(p);
return visited[i];
}
void set_vmask(pair<int, int> p, int x) {
int i = coord(p);
visited[i] = x;
}
void toggle_vmask(pair<int, int> p, Direction d) {
int i = coord(p);
visited[i] ^= 1 << d;
}
};
Direction guard_direction(char c) {
switch (c) {
case '^':
return Direction::U;
case 'v':
return Direction::D;
case '>':
return Direction::R;
case '<':
return Direction::L;
}
return Direction::U;
}
pair<pair<int, int>, Direction> find_guard(Board &board) {
pair<int, int> p(0, 0);
for (p.first = 0; p.first < board.N; p.first++) {
for (p.second = 0; p.second < board.M; p.second++) {
if (board[p] != '.' && board[p] != '#') {
Direction d = guard_direction(board[p]);
return make_pair(p, d);
}
}
}
return make_pair(make_pair(-999, -999), Direction::U);
}
bool isloop(pair<int, int> i, pair<int, int> p, Direction d, Board &board) {
bool ret = false;
board.set_obstruction(i);
while (true) {
auto q = step(p, d);
if (board.is_visited(p, d)) {
ret = true;
break;
}
board.set_visited(p, d);
if (board[q] == board.out_of_bound)
break;
if (board.is_obstruction(q)) {
d = turn(d);
} else {
p = q;
}
}
board.clear_visited();
board.set_clean(i);
return ret;
}
int main() {
string line;
vector<string> lines;
while (getline(cin, line))
lines.push_back(line);
Board board(lines);
int tot = 0;
auto [p, d] = find_guard(board);
pair i(0, 0);
for (i.first = 0; i.first < board.N; i.first++)
for (i.second = 0; i.second < board.M; i.second++)
if (board[i] == '.')
tot += isloop(i, p, d, board);
cout << tot << endl;
return 0;
}
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