#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using pii = pair<ll, ll>;
#define fr first
#define se second
const int N = 5e5+2;
pii a[N];
ll qs[N], curr = 0, ans = 0, currmn = 1e15, currmx = -1e15, mn, mx;
int main()
{
cin.tie(0)->sync_with_stdio(false);
cout.tie(0);
int n;
cin >> n;
for (int i = 1;i <= n;i++) {
cin >> a[i].fr >> a[i].se;
}
sort(a+1, a+n+1);
for (int i = 1; i <= n; ++i){
mn = min(currmn, a[i].fr);
mx = max(currmx, a[i].fr);
if (curr + a[i].se - (mx - mn) < a[i].se){
curr = a[i].se;
currmn = a[i].fr;
currmx = a[i].fr;
}
else{
currmn = mn;
currmx = mx;
curr += a[i].se;
}
ans = max(ans, curr - (currmx - currmn));
}
cout << ans;
}
