#include <bits/stdc++.h>
using namespace std;
#define int long long
using ll = long long;
#define FOR(I, L, R) for(int I(L) ; I <= (int)R ; ++I)
#define FOD(I, R, L) for(int I(R) ; I >= (int)L ; --I)
#define FOA(I, A) for(auto &I : A)
#define print(A,L,R) FOR(OK, L, R){if(A[OK]<=-oo / 10||A[OK]>=oo)cout<<"- ";else cout<<A[OK]<<' ';}cout<<'\n';
#define prints(A) FOA(OK, A){cout<<OK<<' ';}cout << '\n';
#define printz(A,L,R) FOR(OK, 0, L){FOR(KO, 1, R){if(A[OK][KO]>-oo&&A[OK][KO]<oo)cout<<A[OK][KO]<<' ';else cout << "- ";} cout << '\n';}cout << '\n';
#define fs first
#define sd second
#define ii pair<int,int>
#define iii pair<int, ii>
#define all(A) A.begin(), A.end()
#define quickly ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
const int N = 5e5 + 5;
const int mod = 1e9 + 7;
const int oo = 1e18;
int n;
ii a[N];
struct Segment_tree{
int sg[N << 2], lazy[N << 2];
void push_down(int id, int l, int r){
if(lazy[id]){
lazy[id << 1] += lazy[id];
lazy[id << 1 | 1] += lazy[id];
sg[id << 1] += lazy[id];
sg[id << 1 | 1] += lazy[id];
lazy[id] = 0;
}
}
void update(int id, int l, int r, int u, int v, int val){
if(l > v || r < u){
return;
}
if(u <= l && r <= v){
lazy[id] += val;
sg[id] += val;
return;
}
push_down(id, l, r);
int mid = (l + r) >> 1;
update(id << 1, l, mid, u, v, val);
update(id << 1 | 1, mid + 1, r, u, v, val);
sg[id] = max(sg[id << 1], sg[id << 1 | 1]);
}
int get(int id, int l, int r, int u, int v){
if(l > v || r < u){
return -oo;
}
if(u <= l && r <= v){
return sg[id];
}
push_down(id, l, r);
int mid = (l + r) >> 1;
return max(get(id << 1, l, mid, u, v), get(id << 1 | 1, mid + 1, r, u, v));
}
} sg;
signed main(){ quickly
cin >> n;
FOR(i, 1, n){
cin >> a[i].fs >> a[i].sd;
}
sort(a + 1, a + 1 + n);
int ans = 0;
FOR(i, 1, n){
int w = a[i].fs;
int cost = a[i].sd;
sg.update(1, 1, n, 1, i, cost);
sg.update(1, 1, n, i, i, w);
ans = max(ans, sg.get(1, 1, n, 1, i) - w);
}
cout << ans;
}
