from collections import deque

def parse_input(file):
    with open(file, 'r') as f:
        maze = [list(line.strip()) for line in f]
    return maze

def find_start_end(maze):
    start = end = None
    for r, row in enumerate(maze):
        for c, val in enumerate(row):
            if val == 'S':
                start = (r, c)
            elif val == 'E':
                end = (r, c)
    return start, end

def get_neighbors(pos, direction, maze):
    directions = [(0, 1), (1, 0), (0, -1), (-1, 0)]  # East, South, West, North
    r, c = pos
    neighbors = []
    # Move forward
    dr, dc = directions[direction]
    if maze[r + dr][c + dc] != '#':
        neighbors.append(((r + dr, c + dc), direction, 1))  # 1 point for moving forward
    # Turn clockwise
    neighbors.append((pos, (direction + 1) % 4, 1000))  # 1000 points for turning
    # Turn counterclockwise
    neighbors.append((pos, (direction - 1) % 4, 1000))  # 1000 points for turning
    return neighbors

def find_best_paths(maze, start, end):
    directions = [(0, 1), (1, 0), (0, -1), (-1, 0)]  # East, South, West, North
    start_direction = 0  # Start facing East
    queue = deque([(start, start_direction, 0)])  # (position, direction, score)
    visited = set()
    best_score = float('inf')
    best_paths = set()

    while queue:
        pos, direction, score = queue.popleft()
        if (pos, direction) in visited:
            continue
        visited.add((pos, direction))

        if pos == end:
            if score < best_score:
                best_score = score
                best_paths = {pos}
            elif score == best_score:
                best_paths.add(pos)
            continue

        for neighbor, new_direction, cost in get_neighbors(pos, direction, maze):
            new_score = score + cost
            if new_score <= best_score:
                queue.append((neighbor, new_direction, new_score))
                if new_score == best_score:
                    best_paths.add(neighbor)

    return best_paths

def count_best_path_tiles(maze, best_paths):
    count = 0
    for r, row in enumerate(maze):
        for c, val in enumerate(row):
            if (r, c) in best_paths and val != '#':
                count += 1
    return count

def main():
    file = "input.txt"
    maze = parse_input(file)
    start, end = find_start_end(maze)
    best_paths = find_best_paths(maze, start, end)
    result = count_best_path_tiles(maze, best_paths)
    print(result)

main()