#include <stdio.h>
#include <cmath>

int main(void) {
  int a, b, x;
  scanf("%d %d %d", &a, &b, &x);
  if (2*x <= a*a*b) {
    printf("%.10f\n", std::atan(a*b*b/2.0/x) * 180 / M_PI);
  } else {
    printf("%.10f\n", 90 - (std::atan(a*a*a / 2.0 / (a*a*b-x)) * 180 / M_PI));
  }
  return 0;
}
