#include<bits/stdc++.h>
using namespace std;
const double Pi=acos(-1);
double a,b,x;
int main()
{
	scanf("%lf%lf%lf",&a,&b,&x);
	x/=a;
	if(x<=a*b/2)
	{
		double ans=atan(b*b/2/x)/Pi*180;
		printf("%.8lf",ans);
		return 0;
	}
	else
	{
		double ans=atan(2*(a*b-x)/a/a)/Pi*180;
		printf("%.8lf",ans);
	}
	return 0;
}