#include <bits/stdc++.h>
using namespace std;
using ll = long long;
 
struct Strap { int a; ll b; };
int main() {
    int n; cin >> n;
    vector<Strap> s(n);
    for(int i=0;i<n;i++) cin >> s[i].a >> s[i].b;
 
    ll ans = LLONG_MIN;
    for(int root=0; root<n; root++) { // 루트 후보
        vector<ll> dp(2005, LLONG_MIN);
        dp[0] = 0;
        for(int i=0;i<n;i++) {
            if(i==root) continue;
            int t = s[i].a;
            ll val = s[i].b;
            for(int j=2000;j>=0;j--) if(dp[j]!=LLONG_MIN){
                int nj = j + max(0, t-1);
                nj = min(nj,2000);
                dp[nj] = max(dp[nj], dp[j]+val);
            }
        }
        int h = max(0, s[root].a);
        ll root_val = s[root].b;
        ll mx = LLONG_MIN;
        for(int i=0;i<=2000;i++){
            if(dp[i]!=LLONG_MIN && i<=h) mx = max(mx, dp[i]+root_val);
        }
        ans = max(ans, mx);
    }
    cout << ans << "\n";
}

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15
1 -4034
1 3406
0 6062
4 -6824
0 9798
0 4500
0 -1915
1 2137
0 9786
0 7330
0 -9365
2 2730
0 -5797
0 6129
0 8925