//#pragma GCC optimize ("-O3","unroll-loops")
#include<iostream>
#include<string>
#include<algorithm>
#include<vector>
#include<queue>
#include<map>
#include<math.h>
#include<iomanip>
#include<set>
#include<numeric>
#include<cstring>
#include<cstdio>
#include<functional>
#include<bitset>
#include<limits.h>
#include<cassert>
#include<iterator>
#include<complex>
#include<stack>


#define REP(i, n) for(int i = 0;i < n;i++)
#define REPR(i, n) for(int i = n;i >= 0;i--)
#define FOR(i, m, n) for(int i = m;i < n;i++)
#define FORR(i, m, n) for(int i = m;i >= n;i--)
#define SORT(v, n) sort(v, v+n);
#define VSORT(v) sort(v.begin(), v.end());
#define REVERSE(v,n) reverse(v,v+n);
#define VREVERSE(v) reverse(v.begin(), v.end());
#define ll long long
#define pb(a) push_back(a)
#define m0(x) memset(x,0,sizeof(x))
#define print(x) cout<<x<<'\n';
#define pe(x) cout<<x<<" ";
#define lb(v,n) lower_bound(v.begin(), v.end(), n);
#define ub(v,n) upper_bound(v.begin(), v.end(), n);
#define int long long
#define all(x) (x).begin(), (x).end()
#define double long double
#define itn int
#define Endl endl

using namespace std;

int MOD = (ll)1000000000 + 7;
const ll INF = 1e17;
const double pi = acos(-1);
const double EPS = 1e-10;
typedef pair<int, int>P;
const int MAX = 200020;

vector<P>v;
int dp[2020][2020];
signed main() {
	cin.tie(0);
	ios::sync_with_stdio(false);

	itn N; cin >> N;
	REP(i, N) {
		int a, b; cin >> a >> b;
		v.push_back({ b,a });
	}
	VSORT(v); VREVERSE(v);
	dp[0][0] = 0;
	REP(i, N) {
		REP(j, N) {
			if (j == 0) {
				dp[i+1][j] = dp[i][j] + v[i].second + v[i].first*(i);
			}
			else {
				dp[i + 1][j] = min(dp[i][j - 1], dp[i][j] + v[i].second + v[i].first*(max((ll)0,i - j)));
			}
			//pe(i + 1)pe(j)print(dp[i + 1][j]);
		}
	}
	print(dp[N][N / 3]);
}