// editor1
#include <iostream>
#include <vector>
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];
    
    int total = m+n;
    int i=0, j=0;
    int count = 0;
    int mid1=-1, mid2=-1;
    
    while(count<=total/2){
        int val;
        
        if(i<m &&(j>=n||arr1[i]<=arr2[j])){
            val = arr1[i++]
        }else{
            val=arr2[j++]
        }
        if(count==total/2-1)
        mid1 = val;
        
        if(count == total/2)
        mid2=val;
        
        count++;
    }
    
    if(total % 2==1)
    cout<<mid2;
    else
    cout<<(mid1+mid2)/2.0;
    return 0;
}