One world leader, as in ceremonial or actual head of state, of any country, will be sufficient. Apology, dock (or pier, or other oceanfront structure), and response (indicating understanding) required.
50 years seems like a reasonable (generous) approximation of "our lifetimes".
1,000Never mind, I was beaten to it. We don't need duplicates.
@EvanDaniel I like your version better, though Lars has done a fine job as well. Interesting meta-question whether it's better to N/A an accidental duplicate market or just let the arb bots enjoy the free mana.
@dreev I like mine better too, but I don't think this will see enough trading to warrant two versions. I don't think there were useful functional differences; if there were and it was reasonably heavily traded I'd have left it.