
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;

double mediana(const vector<int>&);

int main() {
   vector<int> v;
   int n;
   while (cin >> n) {
      v.push_back(n);
   }
   sort(v.begin(), v.end());
   cout.precision(2);
   cout << mediana(v) << endl;
}
