#include <bits/stdc++.h>
#define ll long long
#define ld long double
#define sp ' '
#define en '\n'
#define smin(a, b) a = min(a, b)
#define smax(a, b) a = max(a, b)
using namespace std;
const int N = 5e5 + 2;
const int M = 1e9;
int mod = 1000000007;
ll st[4 * N];
void Set(int node, int l, int r, int x, ll y) {
if (l == r) {st[node] = y; return;}
int mid = l + r >> 1;
if (x <= mid) Set(2 * node, l, mid, x, y);
else Set(2 * node + 1, mid + 1, r, x, y);
st[node] = max(st[2 * node], st[2 * node + 1]);
}
ll Get(int node, int l, int r, int ql, int qr) {
if (r < ql || qr < l) return 0;
if (ql <= l && r <= qr) return st[node];
int mid = l + r >> 1;
return max(Get(2 * node, l, mid, ql, qr), Get(2 * node + 1, mid + 1, r, ql, qr));
}
int main() {
ios::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
int n;
cin >> n;
vector<array<ll, 2>> a(n);
for (int i = 0; i < n; i++) {
cin >> a[i][0] >> a[i][1];
}
sort(a.begin(), a.end());
for (int i = n - 2; i >= 0; i--) a[i][1] += a[i + 1][1];
for (int i = 0; i < n; i++) Set(1, 0, n - 1, i, a[i][0] + a[i][1]);
ll ans = 0;
for (int i = n - 1; i >= 0; i--) {
ll x = Get(1, 0, n - 1, 0, i);
if (i == n - 1) smax(ans, x - a[i][0]);
else smax(ans, x - a[i][0] - a[i + 1][1]);
}
cout << ans << en;
return 0;
}
