#pragma GCC optimize("O3")
#include<bits/stdc++.h>
#define ll long long
#define endl "\n"
#define AI ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
using namespace std;
struct pr
{
ll a;
ll b;
};
bool comp(pr&x,pr&y)
{
if(x.a==y.a)
return x.b<y.b;
return x.a<y.a;
}
int main()
{
AI
//freopen("input.txt", "r", stdin);
//freopen("output.txt", "w", stdout);
ll n,i,j;
cin>>n;
vector<pr>v(n);
for(i=0;i<n;i++)
cin>>v[i].a>>v[i].b;
ll ans=0;
sort(v.begin(),v.end(),comp);
vector<ll>p(n+1,0);
p[0]=0;
for(i=1;i<=n;i++)
p[i]=p[i-1]+v[i-1].b;
ans=0;
ll mij=0;
ll dp[n];
dp[0]=v[0].b;
ans=max(ans,dp[0]);
for(i=1;i<n;i++)
{
dp[i]=max(v[i].b,dp[i-1]+v[i].b-(v[i].a-v[i-1].a));
ans=max(dp[i],ans);
}
cout<<ans;
}
