// Judges with GCC >= 12 only needs Ofast
// #pragma GCC optimize("O3,no-stack-protector,fast-math,unroll-loops,tree-vectorize")
// MLE optimization
// #pragma GCC optimize("conserve-stack")
// Old judges
// #pragma GCC target("sse4.2,popcnt,lzcnt,abm,mmx,fma,bmi,bmi2")
// New judges. Test with assert(__builtin_cpu_supports("avx2"));
// #pragma GCC target("avx2,popcnt,lzcnt,abm,bmi,bmi2,fma,tune=native")
// Atcoder
// #pragma GCC target("avx2,popcnt,lzcnt,abm,bmi,bmi2,fma")
#include<bits/stdc++.h>
using namespace std;
mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
uniform_real_distribution<> pp(0.0,1.0);
#define int long long
#define pii pair<int,int>
const int inf=1e18;
const int mod=998244353;
const int maxn=500005;
const int maxl=20;
const int maxa=1000005;
int power(int a,int n){
int res=1;
while(n){
if(n&1) res=res*a%mod;
a=a*a%mod;n>>=1;
}
return res;
}
int n;
pii p[maxn];
void solve(){
cin >> n;
for(int i=1;i<=n;i++) cin >> p[i].first >> p[i].second;
sort(p+1,p+n+1);
int Min=inf,ans=-inf;
for(int i=1;i<=n;i++){
p[i].second+=p[i-1].second;
Min=min(Min,-p[i].first+p[i-1].second);
ans=max(ans,p[i].second-p[i].first-Min);
}
cout << ans << '\n';
}
signed main(){
ios_base::sync_with_stdio(false);
cin.tie(NULL);cout.tie(NULL);
int t=1;//cin >> t;
while(t--) solve();
}
