[數論][高精度]Heaven Cow與God Bull

題目描述 __int64 ago,there’s a heaven cow called sjy… A god bull named wzc fell in love with her… As an OI & MOer,wzc gave sjy a quesiton… 給定一個整數n，求一個整數m，知足m<=n，而且m/phi(m)的值最大。 注：phi(m)表明m的歐拉函數，即不大於m且與m互質

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