#include<bits/stdc++.h>
#define ii pair<long long, long long>
#define fi first
#define se second
using namespace std;
const int N = 500002;
const long long inf = 1e16;
int n;
ii a[N];
long long sum[N], r1[N], r2[N], tree[4 * N];
istream & operator >> (istream &inp, ii &m){
inp >> m.fi >> m.se;
return inp;
}
void build(int s, int l, int r){
if(l == r){
tree[s] = r2[l];
return;
}
int mid = (l + r) / 2;
build(2 * s, l, mid);
build(2 * s + 1, mid + 1, r);
tree[s] = min(tree[2 * s], tree[2 * s + 1]);
}
long long get(int s, int l, int r, int u, int v){
if(l > v || r < u)
return inf;
if(l >= u && r <= v)
return tree[s];
int mid = (l + r) / 2;
return min(get(2 * s, l, mid, u, v), get(2 * s + 1, mid + 1, r, u, v));
}
int main(){
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
cin >> n;
for(int i = 1; i <= n; ++i)
cin >> a[i];
sort(a + 1, a + n + 1);
for(int i = 1; i <= n; ++i){
sum[i] = sum[i - 1] + a[i].se;
r1[i] = sum[i] - a[i].fi;
r2[i - 1] = sum[i - 1] - a[i].fi;
}
build(1, 0, n - 1);
long long res = 0;
for(int i = 1; i <= n; ++i)
res = max(res, r1[i] - get(1, 0, n - 1, 0, i - 1));
cout << res;
}
