FILE = "input.txt"

options = [
    (-1, -1), (-1, 0), (0, -1), (1, 1), (1, 0), (0, 1), (-1, 1), (1, -1)
]

def main():
    total = 0
    grid = [list(line.strip()) for line in open(FILE)]
    while True:
        accessible, grid = removal_loop(grid)
        if accessible == 0: break
        total += accessible
    return total

def removal_loop(grid: list[list[str]]) -> tuple[int, list[list[str]]]:
    accessible = 0
    for i in range(len(grid)):
        for j in range(len(grid[0])):
            if grid[i][j] != '@': continue
            nearby = [
                (i + x, j + y)
                for (x, y) in options
                if 0 <= i+x < len(grid) and 0 <= j+y < len(grid[0])
            ]
            nearbyRolls = [
                grid[x][y]
                for (x, y) in nearby
                if grid[x][y] == '@'
            ]
            if len(nearbyRolls) < 4:
                accessible += 1
                grid[i][j] = '.'
    return accessible, grid

if __name__ == "__main__":
    print(main())