#include <bits/stdc++.h>
using namespace std;

int main(){
  double a, b, x;
  cin >> a >> b >> x;
  double ans = 0;
  if(a*b/2 < x/a) ans = atan2(2/a*(a*b-x/a), a) * 360/(2*acos(-1));
  else  ans = atan2(b, 2*x/(a*b)) * 360/(2*acos(-1));
  printf("%.10f", ans);
  return 0;
}