#include <iostream>
#include <climits>
#include <numeric>
#include <cassert>
#include <algorithm>
#include <queue>
#include <map>
#include <stack>
#include <set>
#include <vector>
#include <array>
#include <memory>
#define IN(a,b) (a.find(b) != a.end())
#define p(a,b) make_pair(a,b)
#define readVec(a) for (int64_t __i = 0; __i<(int64_t)a.size();__i++){cin>>a[__i];}
// jimjam
template<typename T>
void pMin(T &a, T b) {if (b<a){a=b;}}
template<typename T>
void pMax(T &a, T b) {if (b>a){a=b;}}
template<typename T>
std::ostream& operator<<(std::ostream& os, const std::vector<T>& c);
template<typename A, typename B>
std::ostream& operator<<(std::ostream& os, const std::pair<A,B>& c) {std::cout << "(" << c.first << ", " << c.second << ")";return os;}
template<typename T>
std::ostream& operator<<(std::ostream& os, const std::vector<T>& c) {
if (c.size() == 0) {os << "{}"; return os;}
os << "{" << c[0];
for (int64_t i = 1; i < (int64_t)c.size(); i++) {os <<", "<<c[i];}
os << "}";
return os;
}
using namespace std;
int main() {
// freopen("input","r",stdin);
ios::sync_with_stdio(0);
cin.tie(0);
int64_t n; cin >> n;
vector<pair<int64_t,int64_t>> arts(n);
for (int64_t i = 0; i < n; i++) {
cin >> arts[i].first >> arts[i].second;
}
sort(arts.begin(),arts.end());
vector<int64_t> prefixValue(n);
prefixValue[0]=arts[0].second;
for (int64_t i = 1; i < n; i++) {
prefixValue[i] = prefixValue[i-1] + arts[i].second;
}
multiset<int64_t> before;
int64_t ans=0;
int64_t minBefore = 1e16;
for (int64_t i = 0; i < n; i++) {
if (minBefore!=1e16) { // idk do calculations
int64_t thisValue = prefixValue[i] - arts[i].first;
// cout << "i=" << i << ": " << thisValue-*before.begin() << endl;
pMax(ans,thisValue-minBefore);
pMax(ans,prefixValue[i] - (arts[i].first - arts[0].first));
}
// add to set
if (i+1<n) pMin(minBefore, prefixValue[i] - arts[i+1].first);
}
cout << ans << endl;
return 0;
}
