using static System.Math;
using System;

public class Hello
{
    static void Main()
    {
        var n = int.Parse(Console.ReadLine().Trim());
        string[] line = Console.ReadLine().Trim().Split(' ');
        var a = new int[n];
        var b = new int[n];
        var bsum = 0L;
        var sum = 0L;
        for (int i = 0; i < n; i++)
        {
            a[i] = int.Parse(line[i * 2]);
            b[i] = int.Parse(line[i * 2 + 1]);
            bsum += b[i];
            sum += a[i] + b[i];
        }
        getAns(n, a, b, bsum, sum);
    }
    static void getAns(int n, int[] a, int[] b, long bsum, long sum)
    {
        var ans = 2 * bsum - sum;
        var asum = 0L;
        for (int i = 0; i < n; i++)
        {
            asum += a[i];
            bsum -= b[i];
            ans = Max(ans, 2 * asum + 2 * bsum - sum);
        }
        Console.WriteLine(ans);
    }
}