#define _USE_MATH_DEFINES
#include <iostream>
#include <cmath>
using namespace std;

int main() {
	double a, b, x;
	cin >> a >> b >> x;
	double d = 2.0 * x >= a * a * b ? 2.0 * (b - x / a / a) : b;
	double e = 2.0 * x >= a * a * b ? a : 2.0 * x / a / b;
	printf("%f\n", atan(d / e) * 180.0 / M_PI);
}
