
import java.util.*;
public class Main{
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    int N = sc.nextInt();
    int A[][] = new int[2][N];
    int S1[] = new int[N+1];
    int S2[] = new int[N+1];
    S1[0]=0;
    S2[0]=0;
    for(int i=0;i<=1;i++){
      for(int j=0;j<N;j++){
        A[i][j]=sc.nextInt();        
      }
    }
    for(int i=1;i<=N;i++){
      S1[i]=S1[i-1]+A[0][i-1];
    }
    for(int i=1;i<=N;i++){
      S2[i]=S2[i-1]+A[1][i-1];
    }
    int ans=0;
    for(int i=1;i<=N;i++){
      ans=Math.max(ans,S1[i]+S2[N]-S2[i-1]);
    }
    System.out.println(ans);
  }

  
} import java.util.*; util.* java public class Main{
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    int N = sc.nextInt();
    int A[][] = new int[2][N];
    int S1[] = new int[N+1];
    int S2[] = new int[N+1];
    S1[0]=0;
    S2[0]=0;
    for(int i=0;i<=1;i++){
      for(int j=0;j<N;j++){
        A[i][j]=sc.nextInt();        
      }
    }
    for(int i=1;i<=N;i++){
      S1[i]=S1[i-1]+A[0][i-1];
    }
    for(int i=1;i<=N;i++){
      S2[i]=S2[i-1]+A[1][i-1];
    }
    int ans=0;
    for(int i=1;i<=N;i++){
      ans=Math.max(ans,S1[i]+S2[N]-S2[i-1]);
    }
    System.out.println(ans);
  }

  
} Main public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    int N = sc.nextInt();
    int A[][] = new int[2][N];
    int S1[] = new int[N+1];
    int S2[] = new int[N+1];
    S1[0]=0;
    S2[0]=0;
    for(int i=0;i<=1;i++){
      for(int j=0;j<N;j++){
        A[i][j]=sc.nextInt();        
      }
    }
    for(int i=1;i<=N;i++){
      S1[i]=S1[i-1]+A[0][i-1];
    }
    for(int i=1;i<=N;i++){
      S2[i]=S2[i-1]+A[1][i-1];
    }
    int ans=0;
    for(int i=1;i<=N;i++){
      ans=Math.max(ans,S1[i]+S2[N]-S2[i-1]);
    }
    System.out.println(ans);
  } main {
    Scanner sc = new Scanner(System.in);
    int N = sc.nextInt();
    int A[][] = new int[2][N];
    int S1[] = new int[N+1];
    int S2[] = new int[N+1];
    S1[0]=0;
    S2[0]=0;
    for(int i=0;i<=1;i++){
      for(int j=0;j<N;j++){
        A[i][j]=sc.nextInt();        
      }
    }
    for(int i=1;i<=N;i++){
      S1[i]=S1[i-1]+A[0][i-1];
    }
    for(int i=1;i<=N;i++){
      S2[i]=S2[i-1]+A[1][i-1];
    }
    int ans=0;
    for(int i=1;i<=N;i++){
      ans=Math.max(ans,S1[i]+S2[N]-S2[i-1]);
    }
    System.out.println(ans);
  } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int N = sc.nextInt(); N sc.nextInt() sc.nextInt sc int A[][] = new int[2][N]; A new int[2][N] 2 N int S1[] = new int[N+1]; S1 new int[N+1] N+1 N 1 int S2[] = new int[N+1]; S2 new int[N+1] N+1 N 1 S1[0]=0 S1[0] S1 0 0 S2[0]=0 S2[0] S2 0 0 for(int i=0;i<=1;i++){
      for(int j=0;j<N;j++){
        A[i][j]=sc.nextInt();        
      }
    } int i=0; int i=0; i 0 i<=1 i 1 i++ i++ i {
      for(int j=0;j<N;j++){
        A[i][j]=sc.nextInt();        
      }
    } {
      for(int j=0;j<N;j++){
        A[i][j]=sc.nextInt();        
      }
    } for(int j=0;j<N;j++){
        A[i][j]=sc.nextInt();        
      } int j=0; int j=0; j 0 j<N j N j++ j++ j {
        A[i][j]=sc.nextInt();        
      } {
        A[i][j]=sc.nextInt();        
      } A[i][j]=sc.nextInt() A[i][j] A[i] A i j sc.nextInt() sc.nextInt sc for(int i=1;i<=N;i++){
      S1[i]=S1[i-1]+A[0][i-1];
    } int i=1; int i=1; i 1 i<=N i N i++ i++ i {
      S1[i]=S1[i-1]+A[0][i-1];
    } {
      S1[i]=S1[i-1]+A[0][i-1];
    } S1[i]=S1[i-1]+A[0][i-1] S1[i] S1 i S1[i-1]+A[0][i-1] S1[i-1] S1 i-1 i 1 A[0][i-1] A[0] A 0 i-1 i 1 for(int i=1;i<=N;i++){
      S2[i]=S2[i-1]+A[1][i-1];
    } int i=1; int i=1; i 1 i<=N i N i++ i++ i {
      S2[i]=S2[i-1]+A[1][i-1];
    } {
      S2[i]=S2[i-1]+A[1][i-1];
    } S2[i]=S2[i-1]+A[1][i-1] S2[i] S2 i S2[i-1]+A[1][i-1] S2[i-1] S2 i-1 i 1 A[1][i-1] A[1] A 1 i-1 i 1 int ans=0; ans 0 for(int i=1;i<=N;i++){
      ans=Math.max(ans,S1[i]+S2[N]-S2[i-1]);
    } int i=1; int i=1; i 1 i<=N i N i++ i++ i {
      ans=Math.max(ans,S1[i]+S2[N]-S2[i-1]);
    } {
      ans=Math.max(ans,S1[i]+S2[N]-S2[i-1]);
    } ans=Math.max(ans,S1[i]+S2[N]-S2[i-1]) ans Math.max(ans,S1[i]+S2[N]-S2[i-1]) Math.max Math ans S1[i]+S2[N]-S2[i-1] S1[i]+S2[N] S1[i] S1 i S2[N] S2 N S2[i-1] S2 i-1 i 1 System.out.println(ans) System.out.println System.out System System.out ans String[] args args public class Main{
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    int N = sc.nextInt();
    int A[][] = new int[2][N];
    int S1[] = new int[N+1];
    int S2[] = new int[N+1];
    S1[0]=0;
    S2[0]=0;
    for(int i=0;i<=1;i++){
      for(int j=0;j<N;j++){
        A[i][j]=sc.nextInt();        
      }
    }
    for(int i=1;i<=N;i++){
      S1[i]=S1[i-1]+A[0][i-1];
    }
    for(int i=1;i<=N;i++){
      S2[i]=S2[i-1]+A[1][i-1];
    }
    int ans=0;
    for(int i=1;i<=N;i++){
      ans=Math.max(ans,S1[i]+S2[N]-S2[i-1]);
    }
    System.out.println(ans);
  }

  
} public class Main{
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    int N = sc.nextInt();
    int A[][] = new int[2][N];
    int S1[] = new int[N+1];
    int S2[] = new int[N+1];
    S1[0]=0;
    S2[0]=0;
    for(int i=0;i<=1;i++){
      for(int j=0;j<N;j++){
        A[i][j]=sc.nextInt();        
      }
    }
    for(int i=1;i<=N;i++){
      S1[i]=S1[i-1]+A[0][i-1];
    }
    for(int i=1;i<=N;i++){
      S2[i]=S2[i-1]+A[1][i-1];
    }
    int ans=0;
    for(int i=1;i<=N;i++){
      ans=Math.max(ans,S1[i]+S2[N]-S2[i-1]);
    }
    System.out.println(ans);
  }

  
} Main

import java.util.*;
public class Main{
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    int N = sc.nextInt();
    int A[][] = new int[2][N];
    int S1[] = new int[N+1];
    int S2[] = new int[N+1];
    S1[0]=0;
    S2[0]=0;
    for(int i=0;i<=1;i++){
      for(int j=0;j<N;j++){
        A[i][j]=sc.nextInt();        
      }
    }
    for(int i=1;i<=N;i++){
      S1[i]=S1[i-1]+A[0][i-1];
    }
    for(int i=1;i<=N;i++){
      S2[i]=S2[i-1]+A[1][i-1];
    }
    int ans=0;
    for(int i=1;i<=N;i++){
      ans=Math.max(ans,S1[i]+S2[N]-S2[i-1]);
    }
    System.out.println(ans);
  }

  
}
