#include<bits/stdc++.h>
using namespace std;
#define int long long
#define yes cout << "YES\n";
#define nl cout << endl;
#define no cout << "NO\n";
#define all(x) x.begin(), x.end()
#define allr(x) x.rbegin(), x.rend()
#define pb push_back
#define ppb pop_back
// #define mp make_pair
#define ff first
#define ss second
#define st string
#define fr(i, x, y) for (int i = x; i < y; i++)
#define FAST ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
// #define MAX 1e18
// #define MIN -1e18
#ifndef ONLINE_JUDGE
#define debug(x) cerr << setw(15) << left << #x << ": "; _print(x); cerr << endl;
#define del cerr << '\n';
#else
#define debug(x)
#define del
#endif
void _print(int t) {cerr << t;}
void _print(string t) {cerr << t;}
void _print(char t) {cerr << t;}
template <typename T, typename V> void _print(const pair<T, V>& p) {cerr << '{'; _print(p.first); cerr << ", "; _print(p.second); cerr << '}';}
template <typename T> void _print(const vector<T>& v) {cerr << '['; for (size_t i = 0; i < v.size(); ++i) {_print(v[i]); if (i != v.size() - 1) cerr << ", ";} cerr << ']';}
template <typename T> void _print(const set<T>& s) {cerr << '{'; bool first = true; for (const auto& x : s) {if (!first) cerr << ", "; _print(x); first = false;} cerr << '}';}
template <typename T> void _print(const multiset<T>& s) {cerr << '{'; bool first = true; for (const auto& x : s) {if (!first) cerr << ", "; _print(x); first = false;} cerr << '}';}
template <typename T, typename V> void _print(const map<T, V>& m) {cerr << '{'; bool first = true; for (const auto& kv : m) {if (!first) cerr << ", "; _print(kv); first = false;} cerr << '}';}
int power(int n, int k){int result = 1;while (k > 0) {if (k & 1) {result = (result * n);}n = (n * n);k >>= 1;}return result;}
int gcd(int a, int b) {if (b > a) {return gcd(b, a);} if (b == 0) {return a;} return gcd(b, a % b);}
int lcm(int a, int b) {return (a / __gcd(a, b)) * b;}
// bool isPrime(int n) {if (n <= 1) return false;if (n == 2) return true;if (n % 2 == 0) return false;for (int i = 3; i * i <= n; i += 2) {if (n % i == 0) return false;}return true;}
/*
sz = size of the art works
val = value of the art works
S = tot value of the choosen artworks
Amx = jegula choose kora oise egular modde max size
Amn = jegula choose kora oise egular modde min size
maximize : S - (Amx - Amn)
*/
const int N = 303;
vector<int> sz(N), val(N);
int n;
map<tuple<int,int,int,int>, int> dp;
int f(int i, int mx, int mn, int sum){
if(i == n){
if(mn == 1e18 || mx == -1e18) return 0;
return sum - (mx - mn);
}
if(dp.count({i, mx, mn, sum})) return dp[{i, mx, mn, sum}];
int not_choose = f(i+1, mx, mn, sum);
int choose = f(i+1, max(mx, sz[i]), min(mn, sz[i]), sum + val[i]);
return dp[{i, mx, mn, sum}] = max(choose, not_choose);
}
void solve(){
cin>>n;
for(int i = 0;i<n;++i){
int a, b; cin>>a>>b;
sz[i] = a;
val[i] = b;
}
cout<<f(0, -1e18, 1e18, 0);
}
int32_t main() {
FAST
#ifndef ONLINE_JUDGE
freopen("error.txt", "w", stderr);
#endif
int t = 1;
// cin >> t;
while (t--) {
solve();
cout << endl;
}
}
