#include <iostream>
#include <queue>
#include <bitset>
#include <stack>
#include <vector>
#include <cstring>
#include <cmath>
#include <unordered_map>
#include <map>
#include <set>
#include <algorithm>
#include <iomanip>
#define F first
#define S second
#define PB push_back
#define PF push_front
#define MP make_pair
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<int,int> pii;
typedef unsigned long long ull;
const int maxn = 5e5 + 100;
const int INF = 1e5;
pair <ll, ll> p[maxn];
ll dp[maxn];
int main (){
ios_base::sync_with_stdio (false);
int n;
cin >> n;
for (int i = 1; i <= n; i++)
cin >> p[i].F >> p[i].S;
sort (p + 1, p + n + 1);
dp[0] = -INF;
ll ans = 0;
for (int i = 1; i <= n; i++) {
dp[i] = p[i].S;
dp[i] = max (dp[i], dp[i - 1] - p[i].F + p[i - 1].F + p[i].S);
ans = max (ans, dp[i]);
}
cout << ans << endl;
}
