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====== Contest Info ====== [[http://codeforces.com/contest/1344|practice link]] ====== Solutions ====== ===== A. Hilbert’s Hotel ===== 签到题。 ===== B. Monopole Magnets ===== 签到题。 ===== C. Quantifier Question ===== **题目大意**：给定一个逻辑命题 $?x_{1}?x_{2}\cdots?x_{n}\bigwedge_{i=1}^{m}(x_{i_{1}}