#include<bits/stdc++.h>
using namespace std;
int a[2005],b[2005],c[2005],n,m,i=1,j=1,k=1;
int main() {
scanf("%d%d",&n,&m);
for(int i = 1; i <= n; i++)
cin>>a[i];
for(int j = 1; j <= m; j++)
cin>>b[j];
while (i <= n && j <= m&&k<(n+m)+1) {
if(a[i] <= b[j]) {
c[k] = a[i];
i++;
} else {
c[k] = b[j];
j++;
}
k++;
}
while (i <= n&&k<(n+m)+1) {
c[k] = a[i];
k++;
i++;
}
while (j <= m&&k<(n+m)+1) {
c[k] = b[j];
k++;
j++;
}
if (n + m % 2)
cout<<c[(n + m) / 2];
else
cout<<(c[(n+m)/2]+c[(n+m)/2-1])/2.0;
}
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