#include <bits/stdc++.h>
using namespace std;
int main() {
  double a, b, x;
  cin >> a >> b >> x;
  double S, height;
  double ans, theta;
  S = x / a;
  if (S > a * b / 2) {
    S = a * b - S;
    height = S / a * 2;
    theta = height / a;
    ans = atan(theta);
    ans = ans * 180 / 3.14159265359;
  } else {
    height = S / b * 2;
    theta = height / b;
    ans = atan(theta);
    ans = ans * 180 / 3.14159265359;
    ans = 90 - ans;
  }
  printf("%.8f\n", ans);
  return 0;
}
