Problem:
Score : 100 points

Problem Statement

In a long narrow forest stretching east-west, there are N beasts. Below, we will call the point that is p meters from the west end Point p. The i-th beast from the west (1 ≤ i ≤ N) is at Point x_i, and can be sold for s_i yen (the currency of Japan) if captured.

You will choose two integers L and R (L ≤ R), and throw a net to cover the range from Point L to Point R including both ends, [L, R]. Then, all the beasts in the range will be captured. However, the net costs R - L yen and your profit will be (the sum of s_i over all captured beasts i) - (R - L) yen.

What is the maximum profit that can be earned by throwing a net only once?

Constraints

1 ≤ N ≤ 2 × 10^5

1 ≤ x_1 < x_2 < ... < x_N ≤ 10^{15}

1 ≤ s_i ≤ 10^9

All input values are integers.

Input

Input is given from Standard Input in the following format:

N
x_1 s_1
x_2 s_2
:
x_N s_N

Output

When the maximum profit is X yen, print the value of X.

Sample Input 1

5
10 20
40 50
60 30
70 40
90 10

Sample Output 1

90

If you throw a net covering the range [L = 40, R = 70], the second, third and fourth beasts from the west will be captured, generating the profit of s_2 + s_3 + s_4 - (R - L) = 90 yen. It is not possible to earn 91 yen or more.

Sample Input 2

5
10 2
40 5
60 3
70 4
90 1

Sample Output 2

5

The positions of the beasts are the same as Sample 1, but the selling prices dropped significantly, so you should not aim for two or more beasts. By throwing a net covering the range [L = 40, R = 40], you can earn s_2 - (R - L) = 5 yen, and this is the maximum possible profit.

Sample Input 3

4
1 100
3 200
999999999999999 150
1000000000000000 150

Sample Output 3

299

Solution in C# (Mono 4.6.2.0) (judge verdict: Accepted)

//#pragma warning disable
using System.Collections;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
using System;
using System.Numerics;
using System.Threading.Tasks;
using static System.Math;
using static System.Console;
class Z { static void Main() => new K(); }
class K
{
	int F() => int.Parse(ReadLine());
	long FL() => long.Parse(ReadLine());
	int[] G() => ReadLine().Split(new char[] { ' ', '\t' }, StringSplitOptions.RemoveEmptyEntries).Select(int.Parse).ToArray();
	long[] GL() => ReadLine().Split(new char[] { ' ', '\t' }, StringSplitOptions.RemoveEmptyEntries).Select(long.Parse).ToArray();
	public const int MOD = 1000000007;
	public K()
	{
		SetOut(new StreamWriter(OpenStandardOutput()) { AutoFlush = false });
		Console.WriteLine(Solve());
		Out.Flush();
	}
	long Solve()
	{
		var N = F();
		var x = new long[N];
		var s = new int[N];
		var sum = new long[N];
		for (int i = 0; i < N; i++)
		{
			var I = GL();
			x[i] = I[0];
			s[i] = (int)I[1];
			if (i == 0) sum[i] = s[i];
			else sum[i] = sum[i - 1] + s[i];
		}
		for (int i = 0; i < N; i++) sum[i] -= x[i];
		var max = new long[N];
		max[N - 1] = sum[N - 1];
		for (var i = N - 2; i >= 0; i--) max[i] = Max(max[i + 1], sum[i]);
		var ans = 0L;
		for (var i = 0; i < N; i++) ans = Max(ans, max[i] - sum[i] + s[i]);
		return ans;
	}
}