#include <bits/stdc++.h>
#define endl '\n'
#define int long long
#pragma GCC optimize("O2")
using namespace std;
int32_t main()
{
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
cout.precision(0);
cout<<fixed;
int n;
cin>>n;
vector<pair<int,int>> x(n);
for (int i = 0; i < n; i++)
{
cin>>x[i].first>>x[i].second;
}
sort(x.begin(),x.end());
int res=0,mxv=-1e9,s=0;
for (int i = 0; i < n; i++)
{
mxv=max(mxv,-s+x[i].first);
res=max(res,s+x[i].second-x[i].first+mxv);
s+=x[i].second;
}
cout<<res<<endl;/*
s: 3 5 2
d: 2 4 11
3+2=
5 10 13
5 15 28
3 8 10
v+min d:2 -max d:i
5 10 12
3 6 1
|
v
-min ->resprefijos sin contar min d
5 8 3
j-1
ahora hallar sumado que Vj=-(∑s[i])+c[j] da mayor
j-1 i=0
o sea mayor: Vj=-(∑s[i])+c[j]
i=0
vc 1 4 -1
V=2 1 4
*/
return 0;
}
