import java.util.*;

public class Main {
    public static void main(String[] args) throws Exception {
        // Your code here!
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int[][] array = new int[2][n];
        for (int i = 0; i < 2; i++) {
            for (int j = 0; j < n; j++) {
                array[i][j] = sc.nextInt();
            }
        }
        
        int[][] ans = new int[2][n];
        ans[0][0] = array[0][0];
        for (int i = 0; i < n-1; i++) {
            ans[0][i+1] = ans[0][i] + array[0][i+1];
        }
        ans[1][0] = array[0][0] + array[1][0];
        for (int i = 1; i < n; i++) {
            ans[1][i] = Math.max(ans[0][i], ans[1][i-1]) + array[1][i];
        }
        System.out.println(ans[1][n-1]);
    }
} import java.util.*; util.* java public class Main {
    public static void main(String[] args) throws Exception {
        // Your code here!
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int[][] array = new int[2][n];
        for (int i = 0; i < 2; i++) {
            for (int j = 0; j < n; j++) {
                array[i][j] = sc.nextInt();
            }
        }
        
        int[][] ans = new int[2][n];
        ans[0][0] = array[0][0];
        for (int i = 0; i < n-1; i++) {
            ans[0][i+1] = ans[0][i] + array[0][i+1];
        }
        ans[1][0] = array[0][0] + array[1][0];
        for (int i = 1; i < n; i++) {
            ans[1][i] = Math.max(ans[0][i], ans[1][i-1]) + array[1][i];
        }
        System.out.println(ans[1][n-1]);
    }
} Main public static void main(String[] args) throws Exception {
        // Your code here!
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int[][] array = new int[2][n];
        for (int i = 0; i < 2; i++) {
            for (int j = 0; j < n; j++) {
                array[i][j] = sc.nextInt();
            }
        }
        
        int[][] ans = new int[2][n];
        ans[0][0] = array[0][0];
        for (int i = 0; i < n-1; i++) {
            ans[0][i+1] = ans[0][i] + array[0][i+1];
        }
        ans[1][0] = array[0][0] + array[1][0];
        for (int i = 1; i < n; i++) {
            ans[1][i] = Math.max(ans[0][i], ans[1][i-1]) + array[1][i];
        }
        System.out.println(ans[1][n-1]);
    } main {
        // Your code here!
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int[][] array = new int[2][n];
        for (int i = 0; i < 2; i++) {
            for (int j = 0; j < n; j++) {
                array[i][j] = sc.nextInt();
            }
        }
        
        int[][] ans = new int[2][n];
        ans[0][0] = array[0][0];
        for (int i = 0; i < n-1; i++) {
            ans[0][i+1] = ans[0][i] + array[0][i+1];
        }
        ans[1][0] = array[0][0] + array[1][0];
        for (int i = 1; i < n; i++) {
            ans[1][i] = Math.max(ans[0][i], ans[1][i-1]) + array[1][i];
        }
        System.out.println(ans[1][n-1]);
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int n = sc.nextInt(); n sc.nextInt() sc.nextInt sc int[][] array = new int[2][n]; array new int[2][n] 2 n for (int i = 0; i < 2; i++) {
            for (int j = 0; j < n; j++) {
                array[i][j] = sc.nextInt();
            }
        } int i = 0; int i = 0; i 0 i < 2 i 2 i++ i++ i {
            for (int j = 0; j < n; j++) {
                array[i][j] = sc.nextInt();
            }
        } {
            for (int j = 0; j < n; j++) {
                array[i][j] = sc.nextInt();
            }
        } for (int j = 0; j < n; j++) {
                array[i][j] = sc.nextInt();
            } int j = 0; int j = 0; j 0 j < n j n j++ j++ j {
                array[i][j] = sc.nextInt();
            } {
                array[i][j] = sc.nextInt();
            } array[i][j] = sc.nextInt() array[i][j] array[i] array i j sc.nextInt() sc.nextInt sc int[][] ans = new int[2][n]; ans new int[2][n] 2 n ans[0][0] = array[0][0] ans[0][0] ans[0] ans 0 0 array[0][0] array[0] array 0 0 for (int i = 0; i < n-1; i++) {
            ans[0][i+1] = ans[0][i] + array[0][i+1];
        } int i = 0; int i = 0; i 0 i < n-1 i n-1 n 1 i++ i++ i {
            ans[0][i+1] = ans[0][i] + array[0][i+1];
        } {
            ans[0][i+1] = ans[0][i] + array[0][i+1];
        } ans[0][i+1] = ans[0][i] + array[0][i+1] ans[0][i+1] ans[0] ans 0 i+1 i 1 ans[0][i] + array[0][i+1] ans[0][i] ans[0] ans 0 i array[0][i+1] array[0] array 0 i+1 i 1 ans[1][0] = array[0][0] + array[1][0] ans[1][0] ans[1] ans 1 0 array[0][0] + array[1][0] array[0][0] array[0] array 0 0 array[1][0] array[1] array 1 0 for (int i = 1; i < n; i++) {
            ans[1][i] = Math.max(ans[0][i], ans[1][i-1]) + array[1][i];
        } int i = 1; int i = 1; i 1 i < n i n i++ i++ i {
            ans[1][i] = Math.max(ans[0][i], ans[1][i-1]) + array[1][i];
        } {
            ans[1][i] = Math.max(ans[0][i], ans[1][i-1]) + array[1][i];
        } ans[1][i] = Math.max(ans[0][i], ans[1][i-1]) + array[1][i] ans[1][i] ans[1] ans 1 i Math.max(ans[0][i], ans[1][i-1]) + array[1][i] Math.max(ans[0][i], ans[1][i-1]) Math.max Math ans[0][i] ans[0] ans 0 i ans[1][i-1] ans[1] ans 1 i-1 i 1 array[1][i] array[1] array 1 i System.out.println(ans[1][n-1]) System.out.println System.out System System.out ans[1][n-1] ans[1] ans 1 n-1 n 1 String[] args args public class Main {
    public static void main(String[] args) throws Exception {
        // Your code here!
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int[][] array = new int[2][n];
        for (int i = 0; i < 2; i++) {
            for (int j = 0; j < n; j++) {
                array[i][j] = sc.nextInt();
            }
        }
        
        int[][] ans = new int[2][n];
        ans[0][0] = array[0][0];
        for (int i = 0; i < n-1; i++) {
            ans[0][i+1] = ans[0][i] + array[0][i+1];
        }
        ans[1][0] = array[0][0] + array[1][0];
        for (int i = 1; i < n; i++) {
            ans[1][i] = Math.max(ans[0][i], ans[1][i-1]) + array[1][i];
        }
        System.out.println(ans[1][n-1]);
    }
} public class Main {
    public static void main(String[] args) throws Exception {
        // Your code here!
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int[][] array = new int[2][n];
        for (int i = 0; i < 2; i++) {
            for (int j = 0; j < n; j++) {
                array[i][j] = sc.nextInt();
            }
        }
        
        int[][] ans = new int[2][n];
        ans[0][0] = array[0][0];
        for (int i = 0; i < n-1; i++) {
            ans[0][i+1] = ans[0][i] + array[0][i+1];
        }
        ans[1][0] = array[0][0] + array[1][0];
        for (int i = 1; i < n; i++) {
            ans[1][i] = Math.max(ans[0][i], ans[1][i-1]) + array[1][i];
        }
        System.out.println(ans[1][n-1]);
    }
} Main
import java.util.*;

public class Main {
    public static void main(String[] args) throws Exception {
        // Your code here!
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int[][] array = new int[2][n];
        for (int i = 0; i < 2; i++) {
            for (int j = 0; j < n; j++) {
                array[i][j] = sc.nextInt();
            }
        }
        
        int[][] ans = new int[2][n];
        ans[0][0] = array[0][0];
        for (int i = 0; i < n-1; i++) {
            ans[0][i+1] = ans[0][i] + array[0][i+1];
        }
        ans[1][0] = array[0][0] + array[1][0];
        for (int i = 1; i < n; i++) {
            ans[1][i] = Math.max(ans[0][i], ans[1][i-1]) + array[1][i];
        }
        System.out.println(ans[1][n-1]);
    }
}
