#include <bits/stdc++.h>
using namespace std;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
int rnd(int l,int r)
{
return l+rng()%(r-l+1);
}
#define fasty ios_base::sync_with_stdio(0),cin.tie(0),cout.tie(0);
#define forinc(x,a,b) for(int x=a;x<=b;x++)
#define fordec(x,a,b) for(int x=a;x>=b;x--)
#define iii pair<ii,int>
#define fi first
#define se second
#define pb push_back
#define ll long long
#define ii pair<int,int>
#define mt make_tuple
#define getbit(x,i) ((x>>(i))&1)
#define batbit(x,i) (x|(1ll<<(i)))
#define tatbit(x,i) (x&~(1<<(i)))
#define endl '\n'
#define all(v) v.begin(), v.end()
#define gg exit(0);
#define int long long
const int N = 5e5 + 100;
ii a[N];
int n;
int sum,res;
signed main()
{
fasty;
cin >> n;
forinc(i,1,n) cin >> a[i].fi >> a[i].se;
sort(a+1,a+n+1);
int best = a[1].fi;
forinc(i,1,n)
{
sum+=a[i].se;
res = max(res , sum - a[i].fi + best);
best = max(best , a[i+1].fi - sum);
}
cout << res;
}
