# include <bits/stdc++.h>
# define int long long
# define vi vector<int>
# define pb push_back
# define pii pair<int, int>
# define fi first
# define se second
# define endl '\n'
# define jess ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
using namespace std;
int n, sum[500005];
pii a[500005];
void solve() {
cin >> n;
for(int i=1; i<=n; i++) {
cin >> a[i].fi >> a[i].se;
}
sort(a+1, a+n+1);
for(int i=1; i<=n; i++) {
sum[i]=sum[i-1]+a[i].se;
}
int mn=1e18, ans=0;
for(int i=1; i<=n; i++) {
int aa=sum[i]-a[i].fi;
mn=min(mn, sum[i-1]-a[i].fi);
ans=max(ans, aa-mn);
}
cout << ans << endl;
}
signed main() {
jess;
solve();
}
