#include<cstdio>
#include<cmath>
const double PI = acos(-1);
int main() {
	double x, a, b;
	scanf("%lf%lf%lf", &a, &b, &x), x /= a;
	if( a * b / 2 >= x ) {
		double p = 2 * x / b;
		printf("%.8lf\n", atan(b / p)/2/PI*360);
	}
	else {
		double p = 2*(a*b - x) / a;
		printf("%.8lf\n", atan(p / a)/2/PI*360);
	}
}