#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define vl vector<ll>
#define vb vector<bool>
#define pb push_back
#define ff(aa, bb, cc) for(ll aa = bb; aa < cc; aa++)
#define pll pair<ll, ll>
#define fi first
#define se second
#define ed "\n"
#define all(aaa) aaa.begin(), aaa.end()
#define rall(aaa) aaa.rbegin(), aaa.rend()
ll MOD = 1e9+7;
int main(){
ll n;
cin >> n;
vector<pll> arr(n);
ff(i, 0, n){
ll a, b;
cin >> a >> b;
arr[i] = {a, b};
}
sort(all(arr));
ll sum = 0, maxx = 0, id = 0;
ff(i, 0, n){
if(arr[i].se > sum+arr[i].se-(arr[i].fi-arr[id].fi)){
id = i;
sum = arr[i].se;
}
else{
sum += arr[i].se;
}
maxx = max(maxx, sum-(arr[i].fi-arr[id].fi));
}
cout << maxx;
}
