#include <bits/stdc++.h>
using namespace std;
#define mod 1000000007
#define ll long long
#define all(v) v.begin(), v.end()
#define fr(n) for(ll i=0;i<n;++i)
#define ctz(x) __builtin_ctzll(x)
#define clz(x) __builtin_clzll(x)
#define pcount(x) __builtin_popcountll(x)
const int dx[] = {-1, 0, 1, 0};
const int dy[] = {0, 1, 0, -1};
// #define cin fin
// #define cout fout
// ifstream fin
// ofstream fout
//const ll maxn = 3e5 + 5;
//int f[maxn],nf[maxn],inv[maxn];
//const int M=998244353;
//void init(){
//inv[1]=1; for (int i=2;i<maxn;i++) inv[i]=M-1ll*(M/i)*inv[M%i]%M;
//f[0]=nf[0]=1; for (int i=1;i<maxn;i++) f[i]=1ll*f[i-1]*i%M,nf[i]=1ll*nf[i-1]*inv[i]%M;
//}
//int C(int x,int y){return 1ll*f[x]*nf[y]%M*nf[x-y]%M;}
void solve(){
ll n;cin>>n;
vector< pair<ll, ll> > v;
ll sum=0;
fr(n){
ll a, b;cin>>a>>b;
sum+=b;
v.push_back(make_pair(a, b));
}
vector<ll> s;
s.push_back(0);
sort(all(v));
sum-=v[n-1].first-v[0].first;
for(ll i=0; i<n-1; i++){
ll temp=v[i+1].first-v[i].first-v[i].second;
s.push_back(temp+s[i]);
}
ll j=0;
vector<ll> s2;s2.push_back(0);
ll mx[n];
mx[n-1]=0;
for(ll i=n-1; i>0; i--){
ll temp=v[i].first-v[i-1].first-v[i].second;
s2.push_back(temp+s[j]);
mx[i-1]=max(mx[i], temp+s[j]);
j++;
}
ll ans=sum;
// cout<<sum<<" ";
// for(ll i=0; i<n; i++){
// cout<<mx[i]<<" ";
// }
for(ll i=0; i<n; i++){
ans=max(ans, sum+s[i]+mx[i]);
}
cout<<ans;
}
int main(){
ios_base::sync_with_stdio(false); cin.tie(NULL);
// ll t;cin>>t;while(t--){solve();cout<<endl;}
solve();
}
