#include <bits/stdc++.h>

int main()
{
	long double pi = std::acos(-1);
	long double a, b, x;
	scanf("%Lf%Lf%Lf", &a, &b, &x);
	x /= a;
	long double ans;
	if (2 * x >= a * b)
		ans = std::atan2(b - (2 * x / a - b), a);
	else
		ans = std::atan2(b, 2 * x / b);
	ans = 180 * (ans / pi);
	printf("%Lf\n", ans);

	return 0;
}