#include <bits/stdc++.h>
//#define DEBUG 1106
#define int long long
#define ll long long
#define ld long double
#define pb emplace_back
#define p_q priority_queue
#define m_p make_pair
#define pii pair<int,int>
#define endl '\n'
#define INIT ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
#define FOR(i,a,b) for(int i = a; i <= b; i++)
#define forn(i,n) for (int i = 0; i < n; i++)
#define forn1(i,n) for (int i = 1; i <= n; i++)
#define all(x) x.begin(),x.end()
#define ft first
#define sd second
#define lowbit(x) (x&(-x))
#define chmax(x,y) x=max(x,y)
#define chmin(x,y) x=min(x,y)
#ifdef DEBUG
#define debug(x) cout << #x << ": " << x << endl;
#else
#define debug(x) 1106;
#endif
using namespace std;
const int N = 3e5+5;
const int M = 2005;
const int inf = 1e9;
const int INF = 1e18;
const int MOD = 1e9+7;
pii a[N];
signed main() {
INIT
#ifdef DEBUG
freopen("input.txt", "r", stdin);
#endif
///////////
int n;
cin >> n;
forn1(i,n) {
cin >> a[i].ft >> a[i].sd;
}
sort(a+1,a+n+1);
forn1(i,n) {
a[i].sd += a[i-1].sd;
}
int mn = -a[1].ft;
int mx = -INF;
forn1(i,n) {
chmin(mn, a[i-1].sd - a[i].ft);
chmax(mx, a[i].sd - a[i].ft - mn);
}
cout << mx;
}
