def compute_col(line):
    """Compute the column of the seat."""
    low: int = 0
    high: int = 7
    for char in line[7:]:
        diff: int = high - low
        if char == 'L':
            # lower half
            high -= int(diff / 2 + 0.5)
        elif char == 'R':
            # upper half
            low += int(diff / 2 + 0.5)
    return high