#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
#define MASK(i) (1ULL << (i))
#define GETBIT(mask, i) (((mask) >> (i)) & 1)
#define ALL(v) (v).begin(), (v).end()
ll max(ll a, ll b){return (a > b) ? a : b;}
ll min(ll a, ll b){return (a < b) ? a : b;}
ll LASTBIT(ll mask){return (mask) & (-mask);}
int pop_cnt(ll mask){return __builtin_popcountll(mask);}
int ctz(ll mask){return __builtin_ctzll(mask);}
int logOf(ll mask){return 63 - __builtin_clzll(mask);}
mt19937_64 rng(chrono::high_resolution_clock::now().time_since_epoch().count());
ll rngesus(ll l, ll r){return l + (ull) rng() % (r - l + 1);}
template <class T1, class T2>
bool maximize(T1 &a, T2 b){
if (a < b) {a = b; return true;}
return false;
}
template <class T1, class T2>
bool minimize(T1 &a, T2 b){
if (a > b) {a = b; return true;}
return false;
}
template <class T>
void printArr(T& container, string separator = " ", string finish = "\n", ostream &out = cout){
for(auto item: container) out << item << separator;
out << finish;
}
template <class T>
void remove_dup(vector<T> &a){
sort(ALL(a));
a.resize(unique(ALL(a)) - a.begin());
}
int main(void){
ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
int n; cin >> n;
vector<pair<ll, ll>> a(n);
for(int i = 0; i<n; ++i) cin >> a[i].first >> a[i].second;
sort(ALL(a), greater<pair<ll, ll>>());
vector<ll> pref(n);
for(int i = 0; i<n; ++i){
pref[i] = a[i].second;
}
for(int i = 1; i<n; ++i) pref[i] += pref[i-1];
for(int i = 0; i<n; ++i) pref[i] += a[i].first;
for(int i = n-2; i>=0; --i) maximize(pref[i], pref[i+1]);
ll ans = 0;
ll s = 0;
for(int i= 0; i<n; ++i){
maximize(ans, pref[i] - a[i].first - s);
s += a[i].second;
}
cout << ans << "\n";
return 0;
}
