#include <iostream>
#include <algorithm>
#include <utility>
using namespace std;
typedef long long ll;
pair<ll,ll> p[2010];
ll dp[2010][2010] = {};
int main(){
	ll i,j,n;
	cin >> n;
	for(i=0;i<n;i++){
		ll a,b; cin >> a >> b;
		p[i] = {-b,a};
	}
	sort(p,p+n);
	for(i=0;i<=n;i++){
		for(j=0;j<=n;j++){
			dp[i][j] = 10000000000000000;
		}
	}
	dp[0][0] = 0;
	for(i=1;i<=n;i++){
		for(j=0;j<=n;j++){
			dp[i][j] = min(dp[i][j],dp[i-1][j]);
			dp[i][j+1] = min(dp[i][j+1],dp[i-1][j] + p[i-1].second - p[i-1].first*j);
		}
	}
	cout << dp[n][n - n/3] << endl;
}