[数论][高精度]Heaven Cow与God Bull

题目描述 __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… 给定一个整数n，求一个整数m，知足m<=n，而且m/phi(m)的值最大。 注：phi(m)表明m的欧拉函数，即不大于m且与m互质

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