def solve_islands(grid):
    rows, cols = len(grid), len(grid[0])
    visited = set() # Or modify grid directly to '#' to save space

    def dfs(r, c):
        # 1. Base Case: Out of bounds or already visited/invalid
        if (r < 0 or r >= rows or c < 0 or c >= cols or
            (r, c) in visited or grid[r][c] == "0"):
            return 0
        
        # 2. Mark visited
        visited.add((r, c))
        
        # 3. Recurse (Summing results if needed, e.g., area)
        size = 1
        size += dfs(r + 1, c)
        size += dfs(r - 1, c)
        size += dfs(r, c + 1)
        size += dfs(r, c - 1)
        return size

    # 4. Main loop to find disconnected components
    max_area = 0
    for r in range(rows):
        for c in range(cols):
            if grid[r][c] == "1" and (r, c) not in visited:
                max_area = max(max_area, dfs(r, c))
    return max_area