import java.util.Scanner;

public class Sushi {

    public static void main(String[] args) {
        
        Scanner scanner = new Scanner(System.in);
        
        int n = scanner.nextInt();
        
        int[] sushi = new int[1000];
        
        for(int i=0;i<n;i++){
            sushi[i] = scanner.nextInt();
        }
        
        int sum = 0;
        int sum2 = 0;
        
        for(int i=0;i<n;i++){
            if(sushi[i] < sushi[i+1]){
                sum += sushi[i+1];
                i = i+2;
            }else{
                sum += sushi[i];
                i++;
            }
        }
        
        for(int i=0;i<n;i++){
            if(sushi[i] < sushi[i+1]){
                sum2 += sushi[i+1];
                i = i+2;
            }else if(sushi[i+1] < sushi[i+2]){
                sum2 += sushi[i+2];
                i=i+3;
            }else{
                sum2 += sushi[i];
                i++;
            }
        }
        
        if(sum < sum2){
            System.out.println(sum2);
        }else{
            System.out.println(sum);
        }
    }
    
}