///TRAN THAI BAO :3
#include <iostream>
#include <cstdio>
#include <vector>
#include <algorithm>
using namespace std;
#define maxN 500007
int n;
typedef pair<long long, long long> pii;
pii inp[maxN];
long long f[maxN] = {0};
void readData()
{
cin >> n;
for(int i = 1; i <= n; i++)
cin >> inp[i].first >> inp[i].second;
sort(inp+1, inp+n+1);
for(int i = 1; i <= n; i++)
f[i] = f[i-1] + inp[i].second;
}
void solve()
{
long long minMinus = -inp[1].first, ans = inp[1].second;
for(int i = 1; i <= n; i++)
{
minMinus = min(minMinus, f[i-1]-inp[i].first);
ans = max(ans, f[i]-inp[i].first - minMinus);
}
cout << ans;
}
int main()
{
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
readData();
solve();
return 0;
}
