#include <bits/stdc++.h>
#pragma comment(linker, "/STACK:512000000")
using namespace std;
void init() { freopen("input.txt", "rt", stdin); }
long double a, b, l;
long double f(long double t) {
  return b * sqrtl(fabsl(1 - t * t)) + a * t - l * t * sqrtl(fabsl(1 - t * t));
}
long double ans1() {
  if (l <= b + 1e-12) return a;
  return -1;
}
long double calc() {
  long double L = 0, R = 1;
  for (int it = 0; it < int(10000); ++it) {
    long double M1 = L + (R - L) / 3.0;
    long double M2 = R - (R - L) / 3.0;
    if (f(M1) > f(M2) - 1e-12) {
      L = M1;
    } else {
      R = M2;
    }
  }
  return max(f(L), ans1());
}
int main() {
  ios_base::sync_with_stdio(false);
  cin >> a >> b >> l;
  cout.precision(10);
  cout << fixed;
  long double ans = calc();
  swap(a, b);
  ans = max(ans, calc());
  if (ans > l) ans = l;
  if (ans >= 1e-7) {
    cout << ans << endl;
  } else {
    cout << "My poor head =(" << endl;
  }
  return 0;
}
