#include <bits/stdc++.h>
using namespace std;
double x, y, l1, ans, eps = 1e-7;
double calc(double a) {
  double b, ret;
  b = sqrt(l1 * l1 - a * a);
  ret = fabs((b * x + a * y - a * b) / l1);
  return ret;
}
int main() {
  int i, j;
  double l, r, w1, w2, mid1, mid2;
  scanf("%lf%lf%lf", &x, &y, &l1);
  if (l1 <= max(x, y)) {
    ans = min(l1, min(x, y));
    printf("%.10lf\n", ans);
    return 0;
  }
  ans = 1e9;
  l = 0;
  r = l1;
  while (r - l > eps) {
    mid1 = (l * 2 + r) / 3;
    mid2 = (l + r * 2) / 3;
    w1 = calc(mid1);
    w2 = calc(mid2);
    ans = min(ans, min(w1, w2));
    if (w1 < w2)
      r = mid2;
    else
      l = mid1;
  }
  ans = min(ans, l1);
  if (ans > eps)
    printf("%.7lf\n", ans);
  else
    printf("My poor head =(\n");
  return 0;
}
