#include <bits/stdc++.h>
#define fi first
#define se second
using namespace std;
const long long N = 5e5 + 100;
int n;
pair <long long, long long> art[N];
long long f[N];
struct segTree
{
long long st[4 * N], lazy[4 * N];
segTree()
{
for (int i = 0; i < 4 * N; i++)
{
st[i] = -1e18;
lazy[i] = 0;
}
}
void build(int id, int l, int r)
{
if (l > r)
return;
if (l == r)
{
st[id] = f[l] - art[l].fi;
return;
}
int mid = l + r >> 1;
build(id * 2, l, mid);
build(id * 2 + 1, mid + 1, r);
st[id] = max(st[id * 2], st[id * 2 + 1]);
}
void down(int id)
{
st[id * 2] += lazy[id];
st[id * 2 + 1] += lazy[id];
lazy[id * 2] += lazy[id];
lazy[id * 2 + 1] += lazy[id];
lazy[id] = 0;
}
void update(int id, int l, int r, int u, int v, long long val)
{
if (v < l || r < u)
return;
if (u <= l && r <= v)
{
lazy[id] += val;
st[id] += val;
return;
}
int mid = l + r >> 1;
down(id);
update(id * 2, l, mid, u, v, val);
update(id * 2 + 1, mid + 1, r, u, v, val);
st[id] = max(st[id * 2], st[id * 2 + 1]);
}
long long get(int id, int l, int r, int u, int v)
{
if (v < l || r < u)
return -1e18;
if (u <= l && r <= v)
return st[id];
int mid = l + r >> 1;
down(id);
return max(get(id * 2, l, mid, u, v), get(id * 2 + 1, mid + 1, r, u, v));
}
} tree;
void sub3()
{
long long ans = -1e18;
for (int i = 1; i <= n; i++)
{
long long sum = 0;
for (int j = i; j <= n; j++)
{
sum = sum + art[j].se;
ans = max(ans, sum - (art[j].fi - art[i].fi));
}
}
cout << ans;
}
void sub()
{
long long ans = -1e18, sum = 0;
for (int i = 1; i <= n; i++)
f[i] = f[i - 1] + art[i].se;
tree.build(1, 1, n);
for (int i = 1; i <= n; i++)
{
long long tmp = tree.get(1, 1, n, i, n);
ans = max(ans, tmp + art[i].fi);
tree.update(1, 1, n, i, n, -art[i].se);
}
cout << ans;
}
int main()
{
ios_base::sync_with_stdio(false);
cin.tie(NULL); cout.tie(NULL);
cin >> n;
for (int i = 1; i <= n; i++)
cin >> art[i].fi >> art[i].se;
sort(art + 1, art + 1 + n);
if (n <= 5000)
sub3();
else
sub();
return 0;
}
