#include<stdio.h>
#include<iostream>
#include<algorithm>
#include<string>
#include<string.h>
#include<math.h>
#include<stdlib.h>
#include<vector>
#include<queue>
#include<map>
#include<tuple>
#include<bitset>
#include<iomanip>
#define rep(index,num) for(int index=0;index<num;index++)
#define rep1(index,num) for(int index=1;index<=num;index++)
#define scan(argument) cin>>argument
#define prin(argument) cout<<argument<<endl
#define kaigyo cout<<endl
#define eps 1e-15
#define mp(a1,a2) make_pair(a1,a2)
typedef long long ll;
using namespace std;
typedef pair<ll,ll> pll;
typedef pair<int,int> pint;
typedef vector<int> vint;
typedef vector<ll> vll;
typedef vector<pint> vpint;
typedef vector<pll> vpll;
ll INFl=1e+18+1;
int INF=1e+9+1;
int main(){
	int N;
	ll x[200001],s[200001];
	ll ruisekiwa[400001]={};
	ll ruisekimin=0;
	ll ans=0;
	scan(N);
	rep(i,N){
		scan(x[i]);scan(s[i]);
	}
	rep1(i,2*N-1){
		if(i%2){
			ruisekiwa[i]=ruisekiwa[i-1]+s[i/2];
		}
		else{
			ruisekiwa[i]=ruisekiwa[i-1]-(x[i/2]-x[i/2-1]);
		}
		ruisekimin=min(ruisekimin,ruisekiwa[i]);
		ans=max(ans,ruisekiwa[i]-ruisekimin);
	}
	prin(ans);
	return 0;
}
