#include <bits/stdc++.h> using namespace std; typedef long long ll; typedef unsigned long long ull; typedef pair<ll, ll> P; typedef pair<int ,P> P3; typedef pair<P ,P> PP; const ll MOD = ll(1e9+7); const int IINF = INT_MAX; const ll LLINF = LLONG_MAX; const int MAX_N = int(1e5 + 5); const double EPS = 1e-6; const int di[] = {0, 1, 0, -1}, dj[] = {1, 0, -1, 0}; #define REP(i, n) for (int i = 0; i < n; i++) #define REPR(i, n) for (int i = n; i >= 0; i--) #define SORT(v) sort((v).begin(), (v).end()) #define ALL(v) (v).begin(), (v).end() int n, m; ll dp[2005][2005]; vector<P> v; int main() { cin >> n; m = n/3; REP(i,n){ ll a, b; cin >> a >> b; v.push_back({b,a}); } SORT(v); reverse(ALL(v)); REP(i,n+1) fill(dp[i], dp[i]+n+1, LLINF/3); dp[0][0] = 0; for(int i=0;i<n;i++){ ll a = v[i].second, b = v[i].first; dp[i+1][0] = dp[i][0] + b*i + a; for(int j=1;j<=m;j++){ dp[i+1][j] = min(dp[i][j] + b*(i-j) + a, dp[i][j-1]); } } cout << dp[n][m] << endl; return 0; }