def move_on_trail(summits_found: set[tuple[int, int]], map_positions: list[list[int]], current_row: int, current_col: int, next_height: int) -> None:
    row_count = len(map_positions)
    col_count = len(map_positions[0])
    for dir_row, dir_col in ((-1, 0), (1, 0), (0, -1), (0, 1)):
        next_row = current_row + dir_row
        next_col = current_col + dir_col

        if not (0 <= next_row < row_count and 0 <= next_col < col_count):
            continue

        if map_positions[next_row][next_col] == next_height:
            if next_height == 9:
                summits_found.add((next_row, next_col))
            else:
                move_on_trail(summits_found, map_positions, next_row, next_col, next_height + 1)


def get_trailhead_score(map_positions: list[list[int]], head_row: int, head_col: int) -> int:
    summits_reached = set()
    move_on_trail(summits_reached, map_positions, head_row, head_col, 1)
    return len(summits_reached)


data = []
with open("input") as f:
    for line in f:
        data.append([int(elem) for elem in tuple(line.strip())])

count = 0
for row, line in enumerate(data):
    for col, height in enumerate(line):
        if height == 0:
            count += get_trailhead_score(data, row, col)

print(count)