#include <bits/stdc++.h>
using namespace std;
int main(){
   double a,b,x;
   cin >> a >> b >> x;
   if((a*a*b)/2<=x) cout << fixed << setprecision(10)<< atan((2*(a*a*b-x))/(a*a*a))*(180/acos(-1)) << endl;
   else cout << fixed << setprecision(10) << atan((a*b*b)/(2*x))*(180/acos(-1)) << endl;
}