题解：将分针的角度和时针的角度都算出来，大的减小的。

#include <stdio.h>
#include <math.h>

int main() {
	double m1, m2, m;
	double ans, h;
	while (scanf("%lf:%lf", &h, &m) && (h || m)) {
		double temp1 = m * 6;
		double temp2 = h * 30 + 30 * temp1 / 360;
		double ans;
		if (temp1 >= temp2)
			ans = temp1 - temp2;
		else
			ans = temp2 - temp1;
		if (ans > 180)
			ans = 360.0 - ans;
		printf("%.3lf\n", ans);
	}
	return 0;
}