#define _CRT_SECURE_NO_WARNINGS
#include<iostream>
#include<sstream>
#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<climits>
#include<cmath>
#include<string>
#include<vector>
#include<set>
#include<map>
#include<queue>
#include<numeric>
#include<functional>
#include<algorithm>
#include<bitset>
#include<tuple>
#include<unordered_set>
#include<unordered_map>
#include<random>
#include<array>
#include<cassert>
using namespace std;
#define INF (1<<29)
#define rep(i,n) for(int i=0;i<(int)(n);i++)
#define all(v) v.begin(),v.end()
#define uniq(v) v.erase(unique(all(v)),v.end())


long long dp[2001][2001];


int main() {
	ios::sync_with_stdio(0);
	cin.tie(0);

	int n;
	cin >> n;

	vector<pair<int, int>> v;
	rep(i,n) {
		int a, b;
		cin >> a >> b;
		v.emplace_back(b, a);
	}
	sort(all(v));
	reverse(all(v));


	rep(i, n + 1)rep(j, n + 1)dp[i][j] = 1LL << 60;
	dp[0][0] = 0;

	rep(i, n)rep(j, n + 1) {
		dp[i + 1][j] = min(dp[i + 1][j], dp[i][j]);

		if (j < n) {
			long long day = j / 3 * 2 + j % 3;
			int x = min(n, j + 1 + (j % 3 == 1));
			dp[i + 1][x] = min(dp[i + 1][x], dp[i][j] + v[i].second + day * v[i].first);
		}
	}
	cout << dp[n][n] << endl;
	

	return 0;
}