// TEMPLATE
#include <bits/stdc++.h>
using namespace std;
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
#define ordered_set tree<int, null_type, less<int>, rb_tree_tag, tree_order_statistics_node_update>
#define ordered_set_char tree<char, null_type, less<char>, rb_tree_tag, tree_order_statistics_node_update>
#define ordered_set_string tree<string, null_type, less<string>, rb_tree_tag, tree_order_statistics_node_update>
#define ordered_multiset tree<int, null_type, less_equal<int>, rb_tree_tag, tree_order_statistics_node_update>
#define ordered_multiset_char tree<char, null_type, less_equal<char>, rb_tree_tag, tree_order_statistics_node_update>
#define ordered_multiset_string tree<string, null_type, less_equal<string>, rb_tree_tag, tree_order_statistics_node_update>
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
#define int long long
#define ldouble long double
#define ll unsigned long long
// #define int int_fast32_t
#define endl '\n'
#define pii pair<int, int>
#define F first
#define S second
void solve()
{
int n;
cin >> n;
vector<pii> vt(n);
for(int i = 0; i < n; i++){
cin >> vt[i].first >> vt[i].second();
}
sort(vt.begin(), vt.end());
vector<int> dp(n + 1, 0);
dp[0] = vt[0].second;
for(int i = 1; i < n; i++){
dp[i] = max({dp[i], vt[i].second, dp[i - 1] + vt[i].second - (vt[i].first - vt[i - 1].first)});
}
int max_v = 0;
for(int i = 1; i <= n; i++){
max_v = max(max_v, dp[i]);
}
cout << max_v << endl;
}
signed main()
{
ios::sync_with_stdio(false);
cin.tie(0);
int T = 1;
// cin >> T;
while (T--)
solve();
}
