#include <bits/stdc++.h> #define sts(v) stable_sort(v.BE, v.E) #define Rsts(v) stable_sort(v.rBE, v.rE) #define rev(v) reverse(v.BE, v.E) #define BE begin() #define rBE rbegin() #define E end() #define rE rend() #define pb push_back #define ppb pop_back() #define pf push_front #define ppf pop_front() #define F first #define S second using namespace std; using ll = long long; int main(){ ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0); int n; cin >> n; vector<pair<ll, ll>> v(n + 1); for(int i = 1; i <= n; i++){ ll a, b; cin >> a >> b; v[i] = {a, b}; //a -> size b -> val } sts(v); int pos = 0; ll res = 0, ans[n + 1]; ans[0] = 0; for(int i = 1; i <= n; i++){ ll a = v[i].S, b = ans[pos] - v[i].F + v[i].S; ans[i] = max(a, b); res = max(res, ans[i]); ans[i] += v[i].F; if(ans[i] > ans[pos])pos = i; } cout << res << '\n'; return 0; }