#include <bits/stdc++.h>
//mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
//#pragma GCC optimize("Ofast")
//1.0 * clock() / CLOCKS_PER_SEC
#define fi first
#define se second
#define ll long long
#define dl double long
using namespace std;
const ll NN = 1e10 + 7;
const int N = 5e5 + 7;
const int M = 6;
const int mod = 1e9 + 7;
const ll inf = 1e18 + 7;
const dl rf = 1e-14;
const int B = sqrt(N);
int n;
ll a[N];
ll b[N];
ll sum[N];
void solve1()
{
cin >> n;
vector < int > v;
for( int i = 1; i <= n; i++ ){
cin >> a[i] >> b[i];
v.push_back(i);
}
sort( v.begin() , v.end() , [&] ( int i , int j ){
return a[i] < a[j];
} );
set < ll > s;
for( int h = 1; h <= n; h++ ){
int i = v[h - 1];
sum[h] = sum[h - 1] + b[i];
}
ll ans = -1e18;
for( int h = 1; h <= n; h++ ){
int i = v[h - 1];
s.insert( sum[h - 1] - a[i] );
auto x = *s.begin();
ans = max( ans , sum[h] - a[i] - x );
}
cout << ans;
}
int main()
{
ios_base::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
//freopen( "input.txt" , "r" , stdin );
//freopen( "output.txt" , "w" , stdout );
int cghf = 1;//cin >> cghf;
while( cghf-- ){
solve1();
}
}
