3981898_ac_110ms_204k.c

北大大牛代码 1240道题的原代码 超级权威

# include <stdio.h>

int main()
{
	int i, m, n;

	while (scanf("%d",&m) == 1)
	{
		m--;
		n = m;
		if(m % 2 == 0)
			n /= 2;
		while (m % 2 == 0)
			m /= 2;
		for (i  = 3; m != 1; i += 2)
		{
			if (m % i == 0)
				n -= n / i;
			while (m % i == 0)
				m /= i;
		}
		printf("%d\n", n);
	}
	return 0;
}