#include <bits/stdc++.h>
using namespace std;
long long mod = 1000000007;
int main() {
  cout << fixed << setprecision(7);
  double a, b, x;
  cin >> a >> b >> x;
  double ans;
  if (x <= a * a * b / 2) {
    double alp = x * 2 / (a * b);
    double res = M_PI / 2 - atan(alp / b);
    ans = res * 180 / M_PI;
  } else {
    x -= a * a * b / 2;
    double alp = x * 2 / (a * a);
    double res = atan((b - alp) / a);
    ans = res * 180 / M_PI;
  }
  cout << ans << "\n";
}
