#include <bits/stdc++.h>
#define FIXED_FLOAT(x) std::fixed <<std::setprecision(20) << (x)
#define all(v) (v).begin(), (v).end()
using namespace std;
#define forn(i,n) for (int i = 0; i < (n); ++i)
#define rforn(i, n) for(int i = (n) - 1;i >= 0;--i)
using ll = long long;
int mod = (ll)1e9 + 7;
#define PI acos(-1)
typedef pair<int, int> pairs;
const int INF = 1e9 + 1;
const int N = 2e5 + 100;
const double eps = 1e-7;
template <class T> using V = vector<T>; // from yosupo
template <class T> using VV = V<V<T>>; // from yosupo
template <typename XPAX>
void ckma(XPAX &x, XPAX y) {
x = (x < y ? y : x);
}
template <typename XPAX>
void ckmi(XPAX &x, XPAX y) {
x = (x > y ? y : x);
}
void solve() {
int n;
cin >> n;
V<pair<ll, ll>> a(n);
forn(i, n)cin >> a[i].first >> a[i].second;
sort(all(a));
V<ll> dp(n, 0);
dp[0] = a[0].second;
for(int i = 1;i < n;++i) {
dp[i] = max(a[i].second, dp[i - 1] - (a[i].first - a[i - 1].first) + a[i].second);
}
ll ans = 0;
forn(i, n)ckma(ans, dp[i]);
cout << ans << '\n';
}
void test_case() {
int t;
cin >> t;
forn(p, t) {
//cout << "Case #" << p + 1 << ": ";
solve();
}
}
int main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
cout.tie(nullptr);
solve();
}
