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[] ue = new int[N];
       int[] shita = new int[N];
       for(int i = 0; i < 2; i++){
           for(int j = 0; j < N; j++){
               A[i][j] = sc.nextInt();
               if(i == 0){
                   if(j==0){
                       ue[j] = A[i][j];
                   } else {
                       ue[j] = ue[j-1] + A[i][j];
                   }
               }
               if(i == 1){
                    if(j==0){
                        shita[j] = A[i][j];
                    } else {
                        shita[j] = shita[j-1] + A[i][j];
                    }
               }
           }
       }
       sc.close();
      
       int max = 0;
       for(int i = 0; i < N; i++){
            if(i != 0)
                max = Math.max(max, ue[i] + (shita[N-1] - shita[i-1]));
            else
                max = Math.max(max, ue[i] + (shita[N-1]));
       }
       System.out.println(max);
    }
} 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[] ue = new int[N];
       int[] shita = new int[N];
       for(int i = 0; i < 2; i++){
           for(int j = 0; j < N; j++){
               A[i][j] = sc.nextInt();
               if(i == 0){
                   if(j==0){
                       ue[j] = A[i][j];
                   } else {
                       ue[j] = ue[j-1] + A[i][j];
                   }
               }
               if(i == 1){
                    if(j==0){
                        shita[j] = A[i][j];
                    } else {
                        shita[j] = shita[j-1] + A[i][j];
                    }
               }
           }
       }
       sc.close();
      
       int max = 0;
       for(int i = 0; i < N; i++){
            if(i != 0)
                max = Math.max(max, ue[i] + (shita[N-1] - shita[i-1]));
            else
                max = Math.max(max, ue[i] + (shita[N-1]));
       }
       System.out.println(max);
    }
} Main public static void main(String args[]){
        Scanner sc = new Scanner(System.in);
        
       int N = sc.nextInt();
       int[][] A = new int[2][N];
       int[] ue = new int[N];
       int[] shita = new int[N];
       for(int i = 0; i < 2; i++){
           for(int j = 0; j < N; j++){
               A[i][j] = sc.nextInt();
               if(i == 0){
                   if(j==0){
                       ue[j] = A[i][j];
                   } else {
                       ue[j] = ue[j-1] + A[i][j];
                   }
               }
               if(i == 1){
                    if(j==0){
                        shita[j] = A[i][j];
                    } else {
                        shita[j] = shita[j-1] + A[i][j];
                    }
               }
           }
       }
       sc.close();
      
       int max = 0;
       for(int i = 0; i < N; i++){
            if(i != 0)
                max = Math.max(max, ue[i] + (shita[N-1] - shita[i-1]));
            else
                max = Math.max(max, ue[i] + (shita[N-1]));
       }
       System.out.println(max);
    } main {
        Scanner sc = new Scanner(System.in);
        
       int N = sc.nextInt();
       int[][] A = new int[2][N];
       int[] ue = new int[N];
       int[] shita = new int[N];
       for(int i = 0; i < 2; i++){
           for(int j = 0; j < N; j++){
               A[i][j] = sc.nextInt();
               if(i == 0){
                   if(j==0){
                       ue[j] = A[i][j];
                   } else {
                       ue[j] = ue[j-1] + A[i][j];
                   }
               }
               if(i == 1){
                    if(j==0){
                        shita[j] = A[i][j];
                    } else {
                        shita[j] = shita[j-1] + A[i][j];
                    }
               }
           }
       }
       sc.close();
      
       int max = 0;
       for(int i = 0; i < N; i++){
            if(i != 0)
                max = Math.max(max, ue[i] + (shita[N-1] - shita[i-1]));
            else
                max = Math.max(max, ue[i] + (shita[N-1]));
       }
       System.out.println(max);
    } 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[] ue = new int[N]; ue new int[N] N int[] shita = new int[N]; shita new int[N] N for(int i = 0; i < 2; i++){
           for(int j = 0; j < N; j++){
               A[i][j] = sc.nextInt();
               if(i == 0){
                   if(j==0){
                       ue[j] = A[i][j];
                   } else {
                       ue[j] = ue[j-1] + A[i][j];
                   }
               }
               if(i == 1){
                    if(j==0){
                        shita[j] = A[i][j];
                    } else {
                        shita[j] = shita[j-1] + A[i][j];
                    }
               }
           }
       } int i = 0; int i = 0; i 0 i < 2 i 2 i++ i++ i {
           for(int j = 0; j < N; j++){
               A[i][j] = sc.nextInt();
               if(i == 0){
                   if(j==0){
                       ue[j] = A[i][j];
                   } else {
                       ue[j] = ue[j-1] + A[i][j];
                   }
               }
               if(i == 1){
                    if(j==0){
                        shita[j] = A[i][j];
                    } else {
                        shita[j] = shita[j-1] + A[i][j];
                    }
               }
           }
       } {
           for(int j = 0; j < N; j++){
               A[i][j] = sc.nextInt();
               if(i == 0){
                   if(j==0){
                       ue[j] = A[i][j];
                   } else {
                       ue[j] = ue[j-1] + A[i][j];
                   }
               }
               if(i == 1){
                    if(j==0){
                        shita[j] = A[i][j];
                    } else {
                        shita[j] = shita[j-1] + A[i][j];
                    }
               }
           }
       } for(int j = 0; j < N; j++){
               A[i][j] = sc.nextInt();
               if(i == 0){
                   if(j==0){
                       ue[j] = A[i][j];
                   } else {
                       ue[j] = ue[j-1] + A[i][j];
                   }
               }
               if(i == 1){
                    if(j==0){
                        shita[j] = A[i][j];
                    } else {
                        shita[j] = shita[j-1] + A[i][j];
                    }
               }
           } int j = 0; int j = 0; j 0 j < N j N j++ j++ j {
               A[i][j] = sc.nextInt();
               if(i == 0){
                   if(j==0){
                       ue[j] = A[i][j];
                   } else {
                       ue[j] = ue[j-1] + A[i][j];
                   }
               }
               if(i == 1){
                    if(j==0){
                        shita[j] = A[i][j];
                    } else {
                        shita[j] = shita[j-1] + A[i][j];
                    }
               }
           } {
               A[i][j] = sc.nextInt();
               if(i == 0){
                   if(j==0){
                       ue[j] = A[i][j];
                   } else {
                       ue[j] = ue[j-1] + A[i][j];
                   }
               }
               if(i == 1){
                    if(j==0){
                        shita[j] = A[i][j];
                    } else {
                        shita[j] = shita[j-1] + A[i][j];
                    }
               }
           } A[i][j] = sc.nextInt() A[i][j] A[i] A i j sc.nextInt() sc.nextInt sc if(i == 0){
                   if(j==0){
                       ue[j] = A[i][j];
                   } else {
                       ue[j] = ue[j-1] + A[i][j];
                   }
               } i == 0 i 0 {
                   if(j==0){
                       ue[j] = A[i][j];
                   } else {
                       ue[j] = ue[j-1] + A[i][j];
                   }
               } if(j==0){
                       ue[j] = A[i][j];
                   } else {
                       ue[j] = ue[j-1] + A[i][j];
                   } j==0 j 0 {
                       ue[j] = A[i][j];
                   } ue[j] = A[i][j] ue[j] ue j A[i][j] A[i] A i j {
                       ue[j] = ue[j-1] + A[i][j];
                   } ue[j] = ue[j-1] + A[i][j] ue[j] ue j ue[j-1] + A[i][j] ue[j-1] ue j-1 j 1 A[i][j] A[i] A i j if(i == 1){
                    if(j==0){
                        shita[j] = A[i][j];
                    } else {
                        shita[j] = shita[j-1] + A[i][j];
                    }
               } i == 1 i 1 {
                    if(j==0){
                        shita[j] = A[i][j];
                    } else {
                        shita[j] = shita[j-1] + A[i][j];
                    }
               } if(j==0){
                        shita[j] = A[i][j];
                    } else {
                        shita[j] = shita[j-1] + A[i][j];
                    } j==0 j 0 {
                        shita[j] = A[i][j];
                    } shita[j] = A[i][j] shita[j] shita j A[i][j] A[i] A i j {
                        shita[j] = shita[j-1] + A[i][j];
                    } shita[j] = shita[j-1] + A[i][j] shita[j] shita j shita[j-1] + A[i][j] shita[j-1] shita j-1 j 1 A[i][j] A[i] A i j sc.close() sc.close sc int max = 0; max 0 for(int i = 0; i < N; i++){
            if(i != 0)
                max = Math.max(max, ue[i] + (shita[N-1] - shita[i-1]));
            else
                max = Math.max(max, ue[i] + (shita[N-1]));
       } int i = 0; int i = 0; i 0 i < N i N i++ i++ i {
            if(i != 0)
                max = Math.max(max, ue[i] + (shita[N-1] - shita[i-1]));
            else
                max = Math.max(max, ue[i] + (shita[N-1]));
       } {
            if(i != 0)
                max = Math.max(max, ue[i] + (shita[N-1] - shita[i-1]));
            else
                max = Math.max(max, ue[i] + (shita[N-1]));
       } if(i != 0)
                max = Math.max(max, ue[i] + (shita[N-1] - shita[i-1]));
            else
                max = Math.max(max, ue[i] + (shita[N-1])); i != 0 i 0 max = Math.max(max, ue[i] + (shita[N-1] - shita[i-1])) max Math.max(max, ue[i] + (shita[N-1] - shita[i-1])) Math.max Math max ue[i] + (shita[N-1] - shita[i-1]) ue[i] ue i (shita[N-1] - shita[i-1]) shita[N-1] shita N-1 N 1 shita[i-1] shita i-1 i 1 max = Math.max(max, ue[i] + (shita[N-1])) max Math.max(max, ue[i] + (shita[N-1])) Math.max Math max ue[i] + (shita[N-1]) ue[i] ue i (shita[N-1]) shita N-1 N 1 System.out.println(max) System.out.println System.out System System.out max 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[] ue = new int[N];
       int[] shita = new int[N];
       for(int i = 0; i < 2; i++){
           for(int j = 0; j < N; j++){
               A[i][j] = sc.nextInt();
               if(i == 0){
                   if(j==0){
                       ue[j] = A[i][j];
                   } else {
                       ue[j] = ue[j-1] + A[i][j];
                   }
               }
               if(i == 1){
                    if(j==0){
                        shita[j] = A[i][j];
                    } else {
                        shita[j] = shita[j-1] + A[i][j];
                    }
               }
           }
       }
       sc.close();
      
       int max = 0;
       for(int i = 0; i < N; i++){
            if(i != 0)
                max = Math.max(max, ue[i] + (shita[N-1] - shita[i-1]));
            else
                max = Math.max(max, ue[i] + (shita[N-1]));
       }
       System.out.println(max);
    }
} 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[] ue = new int[N];
       int[] shita = new int[N];
       for(int i = 0; i < 2; i++){
           for(int j = 0; j < N; j++){
               A[i][j] = sc.nextInt();
               if(i == 0){
                   if(j==0){
                       ue[j] = A[i][j];
                   } else {
                       ue[j] = ue[j-1] + A[i][j];
                   }
               }
               if(i == 1){
                    if(j==0){
                        shita[j] = A[i][j];
                    } else {
                        shita[j] = shita[j-1] + A[i][j];
                    }
               }
           }
       }
       sc.close();
      
       int max = 0;
       for(int i = 0; i < N; i++){
            if(i != 0)
                max = Math.max(max, ue[i] + (shita[N-1] - shita[i-1]));
            else
                max = Math.max(max, ue[i] + (shita[N-1]));
       }
       System.out.println(max);
    }
} 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[] ue = new int[N];
       int[] shita = new int[N];
       for(int i = 0; i < 2; i++){
           for(int j = 0; j < N; j++){
               A[i][j] = sc.nextInt();
               if(i == 0){
                   if(j==0){
                       ue[j] = A[i][j];
                   } else {
                       ue[j] = ue[j-1] + A[i][j];
                   }
               }
               if(i == 1){
                    if(j==0){
                        shita[j] = A[i][j];
                    } else {
                        shita[j] = shita[j-1] + A[i][j];
                    }
               }
           }
       }
       sc.close();
      
       int max = 0;
       for(int i = 0; i < N; i++){
            if(i != 0)
                max = Math.max(max, ue[i] + (shita[N-1] - shita[i-1]));
            else
                max = Math.max(max, ue[i] + (shita[N-1]));
       }
       System.out.println(max);
    }
}