[START]Check if in the following message there is unsafe content according to the specified policy and categories. Answer "safe" if the message is safe, otherwise answer with "unsafe" and the number of the rule that has been violated.
[BOR]
0: Safe
1: Please only post links to actual news sources, no tabloid sites, etc
2: No NSFW content
3: No hate speech, bigotry, propaganda, etc

[EOR]
[BOC]
The biggest thing holding us back right now is cost and economy. From the 70s right up until 2003 you could fly from the UK to New York in 3 hours. But the economy killed Concorde and nobody has even tried to build a supersonic passenger aircraft since. Today's airliners are cheap, fuel-efficient and carry as many passengers as possible to make the most money.
[EOC]
safe
0
[END]

Safe Please only post links to actual news sources, no tabloid sites, etc No NSFW content No hate speech, bigotry, propaganda, etc