import std.stdio, std.conv, std.string, std.range, std.algorithm, std.array,
  std.functional, std.container, std.typecons, std.math;

void main() {
  auto input = readln.split.to!(double[]);
  double a = input[0];
  double b = input[1];
  double x = input[2];

  double s = x / a;
  if(s < a * b / 2) {
    writefln("%.10f", atan2((a*b*b), (2 * x)) * (180 / PI));
  } else {
    writefln("%.10f", atan(2 * (a*b - s) / (a*a)) * (180 / PI));
  }
}
