#include <bits/stdc++.h>
using namespace std;
using i64 = long long;
using pii = pair<i64, i64>;
#pragma GCC optimize("Ofast")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,avx2,mmx,fma,avx,tune=native")
const int N = 500'000, inf = 1'000'000'000;
const i64 infl = 1'000'000'000'000'000'000;
const int mod1 = 1'000'000'009, mod2 = 998'244'353;
const int p1 = 31, p2 = 37;
#define ff first
#define ss second
#define pb push_back
#define ins insert
#define sz(x) (int)(x).size()
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define NO cout << "NO\n"
#define YES cout << "YES\n"
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
int __tc = 1;
i64 n;
pii a[N+5];
void solve() {
sort(a + 1, a + n + 1);
i64 cs = 0, gs = 0;
for (int l = 1, r = 1; r <= n; r++) {
cs += a[r].second;
gs = max(gs, cs - a[r].ff + a[l].ff);
while (cs - a[r].ff + a[l].ff < 0) {
cs -= a[l].ss;
l++;
}
}
cout << gs;
}
int main() {
ios_base::sync_with_stdio(false); cin.tie(nullptr);
// cin >> __tc;
for (int _tc = 1; _tc <= __tc; _tc++) {
cin >> n;
for (int i = 1; i <= n; i++) cin >> a[i].ff >> a[i].ss;
solve();
}
}
