import time


def get_uptime(start_time: float) -> str:
    uptime_seconds = int(time.time() - start_time)
    days = uptime_seconds // 86400
    hours = (uptime_seconds % 86400) // 3600
    minutes = (uptime_seconds % 3600) // 60
    seconds = uptime_seconds % 60
    
    if days > 0:
        return f"{days}d {hours}h {minutes}m {seconds}s"
    elif hours > 0:
        return f"{hours}h {minutes}m {seconds}s"
    elif minutes > 0:
        return f"{minutes}m {seconds}s"
    else:
        return f"{seconds}s"