#include <bits/stdc++.h>
int main(void) {
  double a, b, x;
  double theta, tangent;
  scanf("%lf%lf%lf", &a, &b, &x);
  if (x >= ((a * a * b) / 2)) {
    tangent = (2 * b / a - 2 * x / a / a / a);
    theta = atan(tangent) * (180 / M_PI);
  } else {
    tangent = (2 * x / a / b / b);
    theta = 90 - atan(tangent) * (180 / M_PI);
  }
  printf("%lf", theta);
  return 0;
}
