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// 易错点3：升序排序 → 逻辑完全错误（无法保证"后车不超车"的前提）
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I learned that for 4-SAT, if clause to variable ratio is more than 10, the generated problems become difficult to solve, and the likelihood of formula to be SAT or UNSAT is close to 50%. So I generated 3 types of formulas:
早春二月，贵州乌江源百里画廊。