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];
  writefln("%.10f", atan((a*b*b) / (2 * x)) * (180 / PI));
}
