#include <bits/stdc++.h>
using namespace std;
#define ull unsigned long long
#define lll __int128
#define ll long long
const ll mod = 1e9 + 7;
const ll mod1 = 998244353;
const ll naim = 1e9;
const ll max_bit = 60;
const ull tom = ULLONG_MAX;
const ll MAXN = 100005;
const ll LOG = 20;
const ll NAIM = 1e18;
const ll N = 2e6 + 5;
int main() {
#define pb push_back
#define ff first
#define ss second
#define _ << " " <<
#define yes cout<<"YES\n"
#define no cout<<"NO\n"
#define all(x) x.begin(),x.end()
#define rall(x) x.rbegin(),x.rend()
#define BlueCrowner ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
#define FOR(i, a, b) for (ll i = (a); i < (b); i++)
#define FORD(i, a, b) for (ll i = (a); i >= (b); i--)
// ---------- GCD ----------
auto gcd = [&](ll a, ll b) {
while (b) {
a %= b;
swap(a, b);
}
return a;
};
// ---------- LCM ----------
auto lcm = [&](ll a, ll b) {
return a / gcd(a, b) * b;
};
// ---------- Modular Exponentiation ----------
function<ll(ll, ll, ll)> modpow = [&](ll a, ll b, ll m) {
ll c = 1;
a %= m;
while (b > 0) {
if (b & 1) c = c * a % m;
a = a * a % m;
b >>= 1;
}
return c;
};
// ---------- Modular Inverse (Fermat’s Little Theorem) ----------
function<ll(ll, ll)> modinv = [&](ll a, ll m) {
return modpow(a, m - 2, m);
};
// ---------- Factorials and Inverse Factorials ----------
vector<ll> fact(N), invfact(N);
auto pre_fact = [&](ll n = N-1, ll m = mod) {
fact[0] = 1;
for (ll i = 1; i <= n; i++) fact[i] = fact[i-1] * i % m;
invfact[n] = modinv(fact[n], m);
for (ll i = n; i > 0; i--) invfact[i-1] = invfact[i] * i % m;
};
// ---------- nCr ----------
auto nCr = [&](ll n, ll r, ll m = mod) {
if (r < 0 || r > n) return 0LL;
return fact[n] * invfact[r] % m * invfact[n-r] % m;
};
// ---------- Sieve of Eratosthenes ----------
vector<ll> primes;
vector<bool> is_prime(N);
auto sieve = [&](ll n = N-1) {
fill(is_prime.begin(), is_prime.begin() + n + 1, true);
is_prime[0] = is_prime[1] = false;
for (ll i = 2; i * i <= n; i++) {
if (is_prime[i]) {
for (ll j = i * i; j <= n; j += i)
is_prime[j] = false;
}
}
for (ll i = 2; i <= n; i++)
if (is_prime[i]) primes.pb(i);
};
function<void()> solve = [&]() {
ll n; cin >> n;
map<ll, ll> mp;
FOR(i, 0, n){
ll x, y; cin >> x >> y;
mp[x] += y;
}
vector<pair<ll, ll>> a;
for(auto [x, y] : mp) a.pb({x, y});
ll m = a.size();
ll s = 0;
FOR(i, 0, m) s += a[i].ss;
s -= a[m - 1].ff - a[0].ff;
vector<ll> dp(m, 0);
ll ans = s;
FOR(i, 1, m){
dp[i] = dp[i - 1] - a[i - 1].ss + a[i].ff - a[i - 1].ff;
}
vector<ll> dp1(m, 0);
FORD(i, m - 2, 0){
dp1[i] = dp1[i + 1] - a[i + 1].ss + a[i + 1].ff - a[i].ff;
}
vector<ll> dpmx(m, 0);
vector<ll> dp1mx(m, 0);
dpmx[0] = 0;
if(dp.size() >= 2) dpmx[1] = dp[0];
FOR(i, 2, m){
dpmx[i] = max(dpmx[i - 1], dp[i - 1]);
}
dp1mx.back() = 0;
if(dp.size() >= 2) dp1mx[m - 2] = dp1.back();
FORD(i, m - 3, 0){
dp1mx[i] = max(dp1mx[i + 1], dp1[i + 1]);
}
/*FOR(i, 0, m){
cout << a[i].ff _ a[i].ss << '\n';
}
cout << '\n';
FOR(i, 0, m){
cout << dp[i] <<' ';
}
cout << '\n';
FOR(i, 0, m){
cout << dpmx[i] << ' ';
}
cout << '\n';
FOR(i, 0, m){
cout << dp1[i] << ' ';
}
cout << '\n';
FOR(i, 0, m){
cout << dp1mx[i] << ' ';
}
cout << '\n';*/
ll res = ans;
FOR(i, 0, m){
res = max(res, ans + dpmx[i] + dp1mx[i]);
res = max(res, ans + dpmx[i] + dp1[i]);
res = max(res, ans + dp[i] + dp1mx[i]);
}
cout << res << '\n';
};
//BlueCrowner;
int t = 1; //cin >> t;
while (t--) {
solve();
}
}
