#include<bits/stdc++.h>
#define int long long
#define pii pair<int, int>
#define se second
#define fi first
using namespace std;
const int N = 1e6 + 5;
const int MAXN = LLONG_MAX;
const int mod = 1e9 + 7;
int prf[N], n, dem=0, prf1[N], c[N], mink[N], ans[N], b[N];
int pr[N];
int snt[N];
pii a[N];
signed main() {
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
cout.tie(nullptr);
cin >> n;
for (int i=1; i<=n; ++i) {
cin >> a[i].fi >> a[i].se;
}
sort(a+1, a+n+1);
int sol=0;
mink[0]=-a[1].fi;
prf[0]=0;
for (int i=1; i<=n; ++i) {
prf[i]=prf[i-1]+a[i].se;
c[i]=prf[i]-a[i].fi;
b[i]=prf[i-1]-a[i].fi;
mink[i]=min(mink[i-1], b[i]);
ans[i]=c[i]-mink[i];
sol=max(sol, ans[i]);
}
cout << sol << "\n";
/*for (int i=1; i<=n; ++i) {
cout << c[i] << " " << b[i] << " " << mink[i] << " " << ans[i] << "\n";
}
mink[0]=0;
prf[1]=a[1].se;
mink[1]=a[1].
ans[1]=a[1].se;
for (int i=2; i<=n; ++i) {
prf[i]=prf[i-1]+a[i].se;
c[i]=prf[i]-a[i].fi;
mink[i]=min(mink[i-1], c[i]);
ans=max(ans, c[i]-mink[i]);
}
cout << ans;*/
}
/*
6
4 1
1 5
10 3
9 1
4 2
5 3
3
2 3
11 2
4 5
*/
