#include <bits/stdc++.h>
using namespace std;
int main(){
double a, b, x, ans=0; cin >> a >> b >> x;
if(a*a*b/2<=x){ ans=(180/M_PI)*atan((2*(a*a*b-x))/(a*a*a)); }
else{ ans=(180/M_PI)*atan((a*b*b)/(2*x)); }  
cout << setprecision(12) << ans << "\n";
}