#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);
	if(x<=a*a*b/2) printf("%.10f\n",180*atan(a*b*b/(2*x))/Pi);
	else printf("%.10f\n",180*atan(2*(a*a*b-x)/(a*a*a))/Pi);
}