#include <bits/stdc++.h>
using namespace std;
int main() {
  double pi = acos(-1), rad = 0, deg = 0, l = 0, x, a, b, s = 0;
  cin >> a >> b >> x;
  s = 2 * (x / (b * a));
  if (s >= a) {
    l = -2 * ((x / (a * a)) - b);
    rad = atan(l / a);
  } else {
    rad = atan(b / s);
  }
  deg = rad * 180 / pi;
  cout << deg;
}
