#include <bits/stdc++.h>
using namespace std;
int dp[10000];
int main() {
  int a, b, x;
  double kari, space;
  cin >> a >> b >> x;
  space = a * a * b - x;
  kari = (3.14159265359 / 2) - atan(2 * x / a * b * b);
  if (tan(kari) * a < b) {
    kari = atan(2 * space / a * a * a);
  }
  cout << ((kari) / 2 / 3.14159265359) * 360 << endl;
}
