#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
using vl = vector<ll>;
using pll = pair<ll, ll>;
#define ff first
#define ss second
ll inf = 1e16;
ll ans = 0;
ll n;
vector<pll> v;
void f(ll i, ll mn, ll mx, ll sum)
{
if (i == n)
{
if (mx == -inf || mn == inf)
return;
ans = max(ans, sum - (mx - mn));
return;
}
else
{
ll a = v[i].ff, b = v[i].ss;
f(i + 1, mn, mx, sum);
f(i + 1,min(mn, a),max(mx, a), sum + b);
return;
}
}
int main()
{
ios::sync_with_stdio(0);
cin.tie(nullptr);
cin >> n;
v.assign(n, {0, 0});
for (ll i = 0; i < n; i++)
{
cin >> v[i].ff >> v[i].ss;
}
f(0, inf, -inf, 0);
cout << ans;
return 0;
}
