#include<bits/stdc++.h>
using namespace std;
int main(){
	int N,A[105],B[105],max=0,sum=0;
	cin>>N;
	for(int i = 0;i < N;i++){
		cin>>A[i];
		sum += A[i];
	}
	for(int i = 0;i < N;i++)
		cin>>B[i];
	sum += B[N-1];
	max = sum;
	for(int i = N-2;i>=0;i--){
		sum += B[i];
		sum -= A[i+1];
		if(sum>max) max = sum;
	}
	cout<<max<<endl;
	return 0;
	
} 