// #pragma GCC target ("avx2"){
// #pragma GCC optimization ("O3")
// #pragma GCC optimization ("unroll-loops")
#include <bits/stdc++.h>
#define pll pair<ll, ll>
#define ll long long
#define ld long double
#define pb push_back
#define ff first
#define ss second
#define ins insert
#define pll2 pair<pll,ll>
#define bit(i,k) ((k>>i)&1)
#define pii pair<int,int>
using namespace std;
const long long mod = 998244353;
const ll inf = 1e18;
const ll maxN=1e5+5;
void solve(){
ll n;
cin>>n;
pll a[n+5];
for(int i=1;i<=n;i++){
cin>>a[i].ff>>a[i].ss;
}
sort(a+1,a+n+1);
ll pfs[n+5]={};
for(int i=1;i<=n;i++){
pfs[i]=pfs[i-1]+a[i].ss;
}
ll mn=inf; ll ans=0;
for(int i=1;i<=n;i++){
mn=min(mn,pfs[i-1]-a[i].ff);
ans=max(ans,pfs[i]-a[i].ff-mn);
}
cout<<ans;
}
signed main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
// freopen("photo.inp", "r", stdin);
// freopen("photo.out", "w", stdout);
ll nhim = 1;
// cin >> nhim;
// cout<<nhim<<'\n';
while (nhim--) {
solve();
}
}
