#include <bits/stdc++.h> using namespace std; const int N = 500002; int n; struct art { long long a, b; bool operator < (const art &other) const { return a < other.a; } } v[N]; int main () { cin >> n; for (int i = 1; i <= n; i++) cin >> v[i].a >> v[i].b; sort(v + 1, v + n + 1); long long sum= 0, pref = 1e18, ans = 0; for (int i = 1; i <= n; i++) { pref = min(pref, sum - v[i].a); sum += v[i].b; ans = max(ans, -v[i].a + sum - pref); } cout << ans; return 0; }