#include <bits/stdc++.h>
using namespace std;
#define int long long
#define eb emplace_back
#define mp make_pair
#define pb push_back
#define pp pop_back
#define endl '\n'
#define ff first
#define ss second
#define stop exit(0)
#define sz(x) (int)x.size()
#define pause system("pause")
#define all(x) (x).begin(), (x).end()
#define deb(x) cout << #x << "-" << x << endl
mt19937 mt(time(nullptr));
typedef char chr;
typedef string str;
typedef long long ll;
typedef vector<int> vii;
typedef pair<int, int> pii;
const long long INF = LLONG_MAX;
const int inf = INT_MAX;
const int mod = 1000003;
const int MOD = 1000000007;
const int dx[] = {-1,0,1,0};
const int dy[] = {0,1,0,-1};
const double PI = 2 * acos(0.0);
const int N = 1e6+5;
int n;
pii c[N];
int a[N],b[N];
int pref[N],suf[N];
int sum;
inline void test_case() {
cin >> n;
for (int i = 1; i <= n; i++) {
cin >> c[i].ff >> c[i].ss;
sum += c[i].ss;
}
sort(c+1,c+1+n);
int cur = 0;
for (int i = 1; i <= n-1; i++) {
cur += c[i].ss;
a[i] = c[i+1].ff-c[1].ff-cur;
}
// deb(a[2]);
cur = 0;
for (int i = n; i >= 2; i--) {
cur += c[i].ss;
b[i] = c[n].ff-c[i-1].ff-cur;
}
for (int i = 1; i <= n; i++) {
pref[i] = max(pref[i-1],a[i]);
}
for (int i = n; i >= 1; i--) {
suf[i] = max(suf[i+1],b[i]);
}
int ans = sum-c[n].ff+c[1].ff;
// deb(ans);
int mx = 0;
for (int i = 1; i <= n; i++) {
int cur = pref[i-1]+suf[i+1];
mx = max(mx,cur);
// cout << i << " --> " << pref[i-1] << " " << suf[i+1] << endl;
}
ans += mx;
cout << ans << endl;
}
signed main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
int T = 1;
// cin >> T;
while (T--) test_case();
return 0;
}
