#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef long double ld;
#define REP(i, n) for (int i = 0; i < (n); ++i)
#define REPR(i, n) for (int i = n - 1; i >= 0; --i)
#define FOR(i, m, n) for (ll i = m; i < n; ++i)
#define FORR(i, m, n) for (ll i = m; i >= n; --i)
#define ALL(v) (v).begin(),(v).end()
template<class T>bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T>bool chmin(T &a, const T &b) { if (b<a) { a=b; return 1; } return 0; }
const ll INF=1LL<<60;
const int inf=(1<<30)-1;
const int mod=1e9+7;
int dx[8]={1,0,-1,0,-1,-1,1,1};
int dy[8]={0,1,0,-1,-1,1,-1,1};
int main(){
    cin.tie(0);
    ios::sync_with_stdio(false);
    int n;cin >> n;
    vector<ll> a(n),b(n);
    vector<pair<ll,ll>> p(n);
    REP(i,n){
        cin >> a[i] >> b[i];
        p[i]={b[i],a[i]};
    }
    sort(ALL(p));
    reverse(ALL(p));
    REP(i,n){
        a[i]=p[i].second;
        b[i]=p[i].first;
    }
    vector<vector<ll>> dp(n+1,vector<ll>(n/3+2,INF));
    dp[0][0]=0;
    REP(i,n){
        REP(j,n/3+1){
            if(dp[i][j]==INF){
                continue;
            }
            chmin(dp[i+1][j],dp[i][j]+a[i]+b[i]*(i-j));
            chmin(dp[i+1][j+1],dp[i][j]);
        }
    }
    cout << dp[n][n/3] << endl;
}