import java.io.PrintWriter;
import java.util.Arrays;
import java.util.Random;
import java.util.Scanner;

public class Main implements Runnable { //Runnableを実装する
    public static void main(String[] args) {
//        new Thread(null, new Main(), "", 16 * 1024 * 1024).start(); //16MBスタックを確保して実行
    	new Main().run();
    }
    
    final long INF=Long.MAX_VALUE/3;
    
    long f(long[] a, boolean maximize) {
    	if (a.length==1) return a[0];
    	long ret=maximize?-INF:INF;
    	for (int i=0;i<=a.length;++i) {
    		long[] na=new long[a.length];
    		for (int j=0;j<i;++j) na[j]+=a[j];
    		for (int j=i+1;j<a.length;++j) na[j-1]+=a[j];
    		if (i!=0&&i!=a.length) na[i-1]+=a[i];
    		na=Arrays.copyOf(na, a.length-1);
    		if (maximize) ret=Math.max(ret, f(na, !maximize));
    		else ret=Math.min(ret, f(na, !maximize));
    	}
    	return ret;
    }
    
    long solve_even(long[] a) {
    	int len=a.length/2+1;
    	long sum=Arrays.stream(Arrays.copyOf(a, len)).sum();
    	long ans=sum;
    	for (int i=len;i<a.length;++i) {
    		sum+=-a[i-len]+a[i];
    		ans=Math.min(ans, sum);
    	}
    	return ans;
    }
    
    long solve_odd(long[] a) {
    	int n=a.length;
    	long ok=1;
    	long ng=Long.MAX_VALUE/3;
    	while (ng-ok>1) {
    		long m=(ok+ng)/2;
    		int cnt=0;
    		for (int i=0;i<a.length;++i) {
    			int j=i;
    			long s=a[i];
    			while (j+1<a.length && s<m) {
    				s+=a[j+1];
    				j+=1;
    			}
    			if (s >= m) ++cnt;
    			i=j;
    		}
    		if (cnt>=(n+1)/2) ok=m;
    		else ng=m;
    	}
    	return ok;
    }
    
    long solve(long[] a) {
    	return a.length%2==0?solve_even(a):solve_odd(a);
    }
    
    public void run() {
		Scanner sc=new Scanner(System.in);
		PrintWriter pw=new PrintWriter(System.out);
//		Random rnd=new Random();
//		while (true) {
//			int N=rnd.nextInt(1,10);
//			long[] a=new long[N];
//			for (int i=0;i<a.length;++i) a[i]=rnd.nextInt(1, 10);
//			long solve1=f(a, true);
//			long solve2=solve(a);
//			if (solve1==solve2) tr("ok");
//			else {
//				tr(a);
//				tr(solve1, solve2);
//				return;
//			}
//		}
		
		int N=sc.nextInt();
		long[] A=new long[N];
		for (int i=0;i<N;++i) A[i]=sc.nextInt();
		System.out.println(solve(A));
		pw.close();
	}	
	
	void tr(Object ... o) {System.out.println(Arrays.deepToString(o));}
}