#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define lld long double
#define pb push_back
#define pf push_front
#define F first
#define S second
#define all(a) a.begin(),a.end()
#define IShowSpeed ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL);
const int N=5e5+10;
const int K=505;
const int mod=1e9+7;
const ll inf=1e18+228;
const int dx[]={-1,0,0,1};
const int dy[]={0,-1,1,0};
ll sum[N];
struct node {
ll a,b;
}h[N];
bool cmp(node a, node b){
if(a.a == b.a) return a.b < b.b;
return a.a < b.a;
}
int main()
{
IShowSpeed
ll n,ans=0;
cin>>n;
for(int i=1;i<=n;i++) cin>>h[i].a>>h[i].b;
sort(h+1,h+n+1,cmp);
for(int i=1;i<=n;i++) sum[i]=sum[i-1]+h[i].b;
for(int i=1;i<=n;i++) {
for(int j=i;j<=n;j++) {
ans=max(ans,(sum[j]-sum[i-1])-(h[j].a-h[i].a));
}
}
cout<<ans;
}
/*
1 5
4 1
4 2
5 3
9 1
10 3
*/
