#include <iostream>
#include <vector>
#include <algorithm>
#define ll long long
#define X first
#define Y second
#define endl '\n'
using namespace std;
void speed()
{
ios_base::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
}
int n;
const int MAXN = 500100;
pair<ll, ll> a[MAXN];
ll mx = 0;
void read()
{
mx = 0;
cin >> n;
for (int i = 1; i <= n; i++)
{
cin >> a[i].X >> a[i].Y;
mx = max(mx, a[i].Y);
}
sort(a + 1, a + 1 + n);
}
ll tree[MAXN*4];
ll lazy[MAXN*4];
void push_lazy(int node,int l,int r)
{
if(lazy[node]>0)
{
tree[node]+=lazy[node];
if(l!=r)
{
lazy[node*2]+=lazy[node];
lazy[node*2+1]+=lazy[node];
}
lazy[node]=0;
}
}
void update(int node,int l,int r,int ql,int qr,ll qv)
{
push_lazy(node,l,r);
if(l>=ql &&r<=qr)
{
lazy[node]+=qv;
push_lazy(node,l,r);
return;
}
if(l>qr||r<ql)return;
int mid=(l+r)/2;
update(node*2,l,mid,ql,qr,qv);
update(node*2+1,mid+1,r,ql,qr,qv);
tree[node]=max(tree[node*2],tree[node*2+1]);
}
void solve()
{
update(1,1,n,1,1,a[1].Y);
for(int i=2;i<=n;i++)
{
update(1,1,n,1,i-1,a[i].Y-(a[i].X-a[i-1].X));
update(1,1,n,i,i,a[i].Y);
mx=max(mx,tree[1]);
}
}
signed main()
{
speed();
read();
solve();
cout << mx << endl;
return 0;
}
