#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#define fi first
#define sc second
#define pb push_back
#define int long long
using namespace std;
using namespace __gnu_pbds;
typedef long long ll;
typedef double db;
typedef pair<int, int> pii;
template<typename type>
using ordered_set = tree<type, null_type, less<type>, rb_tree_tag, tree_order_statistics_node_update>;
const int N = 5e5 + 5, mod = 1e9 + 7, inf = 1e18;
const int dl[] = {-1, 0, 1, 0}, dc[] = {0, 1, 0, -1};
const int ddl[] = {-1, -1, -1, 0, 1, 1, 1, 0}, ddc[] = {-1, 0, 1, 1, 1, 0, -1, -1};
mt19937 gen(chrono::steady_clock::now().time_since_epoch().count());
int rng(int lo = 1, int hi = INT_MAX) {
uniform_int_distribution<int> rnd(lo, hi);
return rnd(gen);
}
struct mint {
int val;
mint(int32_t x = 0) {
val = x % mod;
}
mint(long long x) {
val = x % mod;
}
mint operator+(mint x) {
return val + x.val;
}
mint operator-(mint x) {
return val - x.val + mod;
}
mint operator*(mint x) {
return 1LL * val * x.val;
}
void operator+=(mint x) {
val = (*this + x).val;
}
void operator-=(mint x) {
val = (*this - x).val;
}
void operator*=(mint x) {
val = (*this * x).val;
}
friend auto operator>>(istream& in, mint &x) -> istream& {
in >> x.val;
x.val %= mod;
return in;
}
friend auto operator<<(ostream& out, mint const &x) -> ostream& {
out << x.val;
return out;
}
};
int n, rev[N], pref[N], sum[N];
pii v[N];
map<int, int> nrm;
int32_t main()
{
cin.tie(nullptr)->sync_with_stdio(0);
cin >> n;
for(int i=1; i<=n; i++) {
cin >> v[i].fi >> v[i].sc;
nrm[v[i].fi] = 1;
}
int cnt = 0;
for(auto &[key, val] : nrm)
val = ++cnt, rev[val] = key;
for(int i=1; i<=n; i++)
sum[nrm[v[i].fi]] += v[i].sc;
int ans = 0, bst = inf;
for(int i=1; i<=nrm.size(); i++) {
pref[i] = pref[i-1] + sum[i];
bst = min(bst, pref[i-1]-rev[i]);
ans = max(ans, pref[i]-rev[i]-bst);
}
cout << ans;
return 0;
}
