//#pragma GCC optimize("Ofast,unroll-loops")
//#pragma GCC target("avx2,fma,bmi,bmi2,sse4.2,popcnt,lzcnt")
#include <bits/stdc++.h>
#define int long long
#define ll long long
#define vll vector<ll>
#define vllp vector<pair<ll, ll> >
#define vi vector <int>
#define vip vector <pair <int, int> >
#define db double
#define ldb long double
#define pdb pair <double, double>
#define YES cout<<"Yes"
#define NO cout<<"No"
#define nl cout<<"\n"
#define vv vector <vector <int> >
#define pll pair <ll, ll>
#define pi pair <int, int>
#define pb push_back
#define f first
#define s second
using namespace std;
const ll mod=1e9+7;
const ll modx=998244353;
const double eps=1e-9;
const ll INF=INT_MAX;
const ll INFINF=LLONG_MAX;
const int N=5e5;
int n;
vip v;
int dp[N+5];
void input()
{
cin >> n;
for(int i = 1; i <= n; i++)
{
int x, y;
cin >> x >> y;
v.pb({x, y});
}
sort(v.begin(), v.end());
}
void solve()
{
dp[1]=v[0].s;
for(int i = 2; i <= n; i++)
{
dp[i]=v[i-1].s;
dp[i]=max(dp[i], dp[i-1]+v[i-1].s-(v[i-1].f-v[i-2].f));
}
int ans=-INFINF;
for(int i = 1; i <= n; i++)
{
ans=max(ans, dp[i]);
}
cout << ans;
}
signed main()
{
// auto start_time = chrono::high_resolution_clock::now();
// freopen("DNA.inp", "r", stdin);
// freopen("DNA.out", "w", stdout);
ios_base::sync_with_stdio(false); cin.tie(nullptr); cout.tie(nullptr);
int t=1;
// cin >> t;
for(int i = 1; i <= t; i++)
{
input();
solve();
nl;
// cout << flush;
}
// auto end_time = chrono::high_resolution_clock::now();
// double duration = chrono::duration_cast<chrono::milliseconds>(end_time - start_time).count();
// cout << "\n[ " << duration << " ms ]\n";
}
