/*
* imaN
* 49
*
*
**/
#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define FF first
#define SS second
#define pb push_back
#define bp pop_back()
#define int long long
#define ld long double
#define pf push_front
#define Imansoska ios_base::sync_with_stdio(0);cin.tie(0); cout.tie(0);
#define endl cout << "\n"
/*int binpow (int a, int n, int m) {
if (n == 0)
return 1%m;
if (n % 2 == 1)
return binpow (a, n-1,m) * a%m;
else {
int b = binpow (a, n/2,m);
return b * b%m;
}
}
int lcm(int a, int b) {
return (a / __gcd(a, b)) * b;
}*/
const int N = (1e5+13)*5;
const int maxn= 1e6+10;
const int MOD = 1e9 + 7;
const int INF = 1e18 + 7;
int z[N] , a[N] , ans=-INF , n;
void rec(int v,int mn,int mx,int s) {
ans=max(ans,s-(mx-mn));
for ( int i=v+1; i<=n; i++ ) {
rec(i,min(mn,z[i]),max(mx,z[i]),s+a[i]);
}
}
signed main (/*Imansoska*/) {
Imansoska
// freopen("lepus.in","r",stdin);
// freopen("lepus.out","w",stdout);
cin >> n;
for ( int i=1; i<=n; i++ ) {
cin >> z[i] >> a[i];
}
for ( int i=1; i<=n; i++ ) {
rec(i,z[i],z[i],a[i]);
}
cout << ans;
}
