#include <bits/stdc++.h>
#define F first
#define S second
#define fo(i, n1, n, x) for(int i = n1; i <= n; i += x)
#define foo(i, n, n1, x) for(int i = n; i >= n1; i -= x)
using namespace std;
#define int ll
using ll = long long;
using pii = pair<int,int>;
using pll = pair<ll,ll>;
using vi = vector<int>;
const int N = 5e5 + 11;
const ll INF2 = 2e18 + 11;
template<typename T1, typename T2> inline void chmax(T1 &a, T2 b) { if (a < b) a = b; }
int n,t[N*4],pref[N];
pii a[N];
void upd(int v, int l, int r, int pos, int val) {
if (l == r) {
t[v]=val;
return;
}
int md=l+((r - l) >> 1ll);
if (pos <= md) upd(v+v,l,md,pos,val);
else upd(v+v+1,md+1,r,pos,val);
t[v]=max(t[v+v],t[v+v+1]);
}
int get(int v, int l, int r, int left, int right) {
if (left > r || right < l) return 0;
if (left <= l and r <= right) return t[v];
int md=l+((r-l)>>1ll);
return max(get(v+v,l,md,left,right),get(v+v+1,md+1,r,left,right));
}
main() {
cin>>n;
fo(i,1,n,1) cin>>a[i].F>>a[i].S;
sort(a+1,a+n+1, greater<pii>());
fo(i,1,n,1) pref[i]=pref[i-1]+a[i].S;
foo(i,n,2,1) upd(1,1,n,i,pref[i]+a[i].F);
int ans=-INF2;
fo(l,1,n,1) chmax(ans,get(1,1,n,l,n)-pref[l-1]-a[l].F);
cout<<ans;
return 0;
}
