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

int main(void){
  int n;
  cin>>n;
  vector<int> in(n);
  for(int i=0;i<n;i++){
    cin>>in[i];
  }
  if(n%2){
    //odd
    cout<<in[n/2+1]<<endl;
  }else{
    //even
    cout<<1.0*(in[n/2]+in[n/2+1])/2<<endl;
  }

}