#include <bits/stdc++.h>
using namespace std;
int main() {
    double a,b,x;
    cin >> a >> b >> x;
    double ans;
if(a*a*b/2<=x){
    ans=atan((2*a*a*b-2*x)/(a*a*a));
}
else{
    ans=atan(a*b*b/(2*x));
}
cout << fixed << setprecision(10) << ans*180/3.14159265358979;
}