#include <bits/stdc++.h>
using namespace std;
#define int ll
#define FOR(i,s,e) for(ll i = s; i <= (ll)e; ++i)
#define DEC(i,s,e) for(ll i = s; i >= (ll)e; --i)
#define IAMSPEED ios_base::sync_with_stdio(false); cin.tie(0);
#ifdef LOCAL
#define db(x) cerr << #x << "=" << x << "\n"
#define db2(x, y) cerr << #x << "=" << x << " , " << #y << "=" << y << "\n"
#define db3(a,b,c) cerr<<#a<<"="<<a<<","<<#b<<"="<<b<<","<<#c<<"="<<c<<"\n"
#define dbv(v) cerr << #v << ":"; for (auto ite : v) cerr << ite << ' '; cerr <<"\n"
#define dbvp(v) cerr << #v << ":"; for (auto ite : v) cerr << "{" << ite.f << ',' << ite.s << "} "; cerr << "\n"
#define dba(a,ss,ee) cerr << #a << ":"; FOR(ite,ss,ee) cerr << a[ite] << ' '; cerr << "\n"
#define reach cerr << "LINE: " << __LINE__ << "\n";
#else
#define db(x)
#define db2(x,y)
#define db3(a,b,c)
#define dbv(v)
#define dbvp(v)
#define dba(a,ss,ee)
#define reach
#endif
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
#define ll long long
#define pb push_back
#define eb emplace_back
#define all(x) (x).begin(), (x).end()
#define f first
#define s second
#define g0(x) get<0>(x)
#define g1(x) get<1>(x)
#define g2(x) get<2>(x)
#define g3(x) get<3>(x)
typedef pair <ll, ll> pi;
typedef tuple<ll,ll,ll> ti3;
typedef tuple<ll,ll,ll,ll> ti4;
ll rand(ll a, ll b) { return a + rng() % (b-a+1); }
const int MOD = 1e9 + 7;
const int inf = (int)1e9 + 500;
const long long oo = (ll)1e18 + 500;
template <typename T> bool chmax(T& a, const T b) { return a<b ? a = b, 1 : 0; }
template <typename T> bool chmin(T& a, const T b) { return a>b ? a = b, 1 : 0; }
const int MAXN = 500005;
int n;
pi A[MAXN];
int lf[MAXN], rg[MAXN];
int32_t main()
{
IAMSPEED
cin >> n;
FOR(i,1,n) cin>> A[i].f >> A[i].s;
sort(A+1,A+n+1,[](pi a, pi b) {
return a.f < b.f;
});
int sum = 0;
FOR(i,2,n) {
sum -= A[i-1].s;
sum += A[i].f - A[i-1].f;
lf[i] = sum;
lf[i] = max(lf[i], lf[i-1]);
}
int ans=0;
sum = 0;
int tot =0 ;
FOR(i,1,n) tot += A[i].s;
tot -= A[n].f-A[1].f;
chmax(ans, tot);
chmax(ans, tot + lf[n]);
DEC(i,n-1,1) {
sum -= A[i+1].s;
sum += A[i+1].f - A[i].f;
chmax(ans, tot + sum + lf[i]);
}
cout << ans;
}
