The USA TST, or USA Team Selection Test, is a test administered to the top ~30 scorers on the TSTST. The results are used to determine the team that is sent to the IMO (although not the sole determining factor). Nowadays, it consists of 6 problems over 2 days, like the USAMO. The questions (especially recently) are also noticeably harder than respectively problems on the USAMO, usually.
Problem 1/4/7: 7
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