#include <algorithm>
#include <bitset>
#include <complex>
#include <deque>
#include <exception>
#include <fstream>
#include <functional>
#include <iomanip>
#include <ios>
#include <iosfwd>
#include <iostream>
#include <istream>
#include <iterator>
#include <limits>
#include <limits.h>
#include <list>
#include <cmath>
#include <locale>
#include <map>
#include <memory>
#include <new>
#include <numeric>
#include <ostream>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <stdio.h>
#include <stdexcept>
#include <streambuf>
#include <string>
#include <typeinfo>
#include <utility>
#include <valarray>
#include <vector>
#include <unordered_map>
using namespace std;
#define int long long
#define MOD 1000000007
#define INF 2000000000
#define IN 100001
#define LOG 20
#define MINF -2000000000
#define all(x) x.begin(),x.end()
#define fast_io ios_base::sync_with_stdio(false);cin.tie(nullptr);
void solution(){
int n; cin >> n;
vector<pair<int, int> > arr;
for(int i = 0; i < n; i++){
int a,b; cin >> a >> b;
arr.push_back({a,b});
}
sort(all(arr));
int cur = 0;
int ans = 0;
for(int i = 0; i < n; i++){
cur += arr[i].second;
cur = max(cur , arr[i].first + arr[i].second);
ans = max(ans , cur - arr[i].first);
}
cout << ans << endl;
}
signed main() {
fast_io
int t = 1;
//cin >> t;
while (t--) {
solution();
}
return 0;
}
