// happy
//#pragma GCC optimize("O3,unroll-loops")
//#pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")
#include <bits/stdc++.h>
#define int long long
//#define ll long long
#define fi first
#define se second
#define pb push_back
using namespace std;
typedef pair<int,int> pii;
typedef tuple<int,int,int> tp;
const int N = 1e6 + 5;
const int oo = 1e16;
const int mod = 1e9 + 7;
const int base = 29; // >= so pt pb max
int n, a[N], b[N], sum, s[N], st[N << 2], ans;
pii p[N];
void update(int i,int x){
i += n - 1;
st[i] = max(st[i], x);
while(i > 1){
i /= 2;
st[i] = max(st[i], x);
}
}
int get(int l,int r){
r++;
int ret = -oo;
for(l += n - 1, r += n - 1; l < r; l /= 2, r /= 2){
if(l & 1) ret = max(ret, st[l ++]);
if(r & 1) ret = max(ret, st[-- r]);
}
return ret;
}
signed main(){
ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
#define task "v"
if(fopen(task ".inp","r")){
freopen(task ".inp","r",stdin);
freopen(task ".out","w",stdout);
}
cin >> n;
for(int i = 1; i <= n; i ++){
cin >> a[i] >> b[i];
p[i] = {a[i], b[i]};
}
sort(p + 1, p + n + 1);
update(1, 0 + p[1].fi);
for(int i = 1; i <= n; i ++){
s[i] = s[i - 1] + p[i].se;
int u = get(1, i) - p[i].fi + s[i];
// cout << p[i].fi << " " << p[i].se << " h\n";
// cout << u << " " << i << " " << -s[i]+p[i + 1].fi << " " << get(1, i) << " " << s[i] << " " << " g\n";
ans = max(ans, u);
if(i + 1 <= n) update(i + 1, -s[i]+p[i + 1].fi);
}
cout << ans;
}
