
#include "bits/stdc++.h"
using namespace std;

#define DEBUG(x) cout<<#x<<": "<<x<<endl;
#define DEBUG_VEC(v) cout<<#v<<":";for(int i=0;i<v.size();i++) cout<<" "<<v[i]; cout<<endl

typedef long long ll;
#define vi vector<int>
#define vl vector<ll>
#define vii vector< vector<int> >
#define vll vector< vector<ll> >
#define vs vector<string>
#define pii pair<int,int>
#define pis pair<int,string>
#define psi pair<string,int>
#define pll pair<ll,ll>
const int inf = 1000000001;
const ll INF = 2e18 * 2;
#define MOD 1000000007
#define mod 1000000009
#define pi 3.14159265358979323846
#define Sp(p) cout<<setprecision(15)<< fixed<<p<<endl;
int dx[4] = { 1,0,-1,0 }, dy[4] = { 0,1,0,-1 };
int dx2[8] = { 1,1,0,-1,-1,-1,0,1 }, dy2[8] = { 0,1,1,1,0,-1,-1,-1 };


int main() {
	int n, i, j;
	cin >> n;
	vl x(n), s(n);
	for (i = 0; i < n; i++) {
		cin >> x[i] >> s[i];
	}
	vl sum(n + 1);
	vl left(n), right(n);
	sum[0] = 0;
	for (i = 0; i < n; i++) {
		sum[i + 1] = sum[i] + s[i];
		left[i] = sum[i] - x[i];
		right[i] = sum[i + 1] - x[i];
	}
	/*
	DEBUG_VEC(left);
	DEBUG_VEC(right);
	*/
	ll ans = -INF;
	deque<ll> dqr;
	for (i = 0; i < n; i++) {
		while (!dqr.empty() && right[dqr.back()] < right[i]) {
			dqr.pop_back();
		}
		dqr.push_back(i);
	}
	

	for (i = 0; i < n; i++) {
		/*
		for (j = 0; j < dqr.size(); j++) {
			cout << dqr[j] << " ";
		}
		cout << endl;
		*/
		ans = max(ans, right[dqr[0]] - left[i]);
		while (!dqr.empty() && dqr.front() <= i) {
			dqr.pop_front();
		}
	}
	cout << ans << endl;
}