#include <bits/stdc++.h>
using namespace std;
#pragma GCC optimize("O3,unroll-loops")
#pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")
typedef long long ll;
typedef vector<int> vi;
typedef pair<int, int> pi;
#define pb push_back
#define mp make_pair
#define f first
#define s second
void solve(){
int n;
cin >> n;
vector<pair<ll, ll>> a(n);
for(int i = 0; i < n; i++)
cin >> a[i].f >> a[i].s;
sort(a.begin(), a.end());
vector<ll> dp(n);
dp[n-1] = a[n-1].s;
for(int i = n-2; i >= 0; i--)
dp[i] = max(a[i].s, a[i].s + dp[i+1] - (a[i+1].f - a[i].f));
cout << *max_element(dp.begin(), dp.end()) << '\n';
}
int main(){
//freopen("input.txt", "r", stdin);
//freopen("test.out", "w", stdout);
ios::sync_with_stdio(0); cin.tie(0);
int t = 1;
//cin >> t;
while(t--){
solve();
}
}
