#include<iostream>
#include<vector>
#include<algorithm>
using namespace std;
int main(){
    int m,n;
    cin>>m>>n;
    if(m<0||n<0){
        cout<<"Invalid input";
        return 0;
    }
    vector<int> arr1(m),arr2(n);
    for (int i =0;i<m;i++)
          cin>>arr1[i];
    for (int i=0;i<n;i++)
         cin>>arr2[i];
         
         vector<int>merged;
         merged.insert(merged.end()arr1.begin(), arr1.end());
         merged.insert(merged.end()arr2.begin(), arr2.end());
         
     sort (merged.begin(),merged.end());
     
     int size=merged.size();
     
     if(size %2==0)
         cout<<(merged[size/2-1]+
merged[size/2])/2.0;
   else
      cout<<merged[size/2];
      
      return 0;
    
}