#include <bits/stdc++.h>
#define int long long
#define task "task"
#define fi first
#define se second
using namespace std;
const int ma = 1e6 + 4;
int n, st[ma * 4], prefix[ma];
pair<int, int> a[ma];
vector<int> v;
void Read()
{
cin >> n;
for (int i = 1; i <= n; i++) cin >> a[i].fi >> a[i].se;
}
void pre()
{
for (int i = 1; i <= n; i++) prefix[i] = prefix[i - 1] + a[i].se;
}
void update(int id, int l, int r, int pos, int val)
{
if (l == r)
{
st[id] = val;
return;
}
int mid = (l + r) / 2;
if (pos <= mid) update(id * 2, l, mid, pos, val);
else update(id * 2 + 1, mid + 1, r, pos, val);
st[id] = max(st[id * 2], st[id * 2 + 1]);
return;
}
int get(int id, int tl, int tr, int l, int r)
{
if (l > tr || r < tl) return 0;
if (l <= tl && tr <= r) return st[id];
int mid = (tl + tr) / 2;
return max(get(id * 2, tl, mid, l, r), get(id * 2 + 1, mid + 1, tr, l, r));
}
void solve()
{
sort(a + 1, a + 1 + n);
pre();
int res = LLONG_MIN;
for (int i = 1; i <= n; i++) res = max(res, a[i].se);
for (int i = 1; i <= n; i++)
{
int tmp = prefix[i] - a[i].fi + get(1, 0, n, 0, i - 1);
res = max(res, tmp);
update(1, 0, n, i, a[i].fi - prefix[i - 1]);
}
cout << res;
}
signed main()
{
if(fopen(task ".INP", "r"))
{
freopen(task ".INP", "r", stdin);
freopen(task ".OUT", "w", stdout);
}
ios_base::sync_with_stdio(false);
cin.tie(NULL);
Read();
solve();
return 0;
}
