#include <bits/stdc++.h>
#define mp make_pair
#define all(vec) vec.begin(),vec.end()
using namespace std;
using ll=long long;
using P=pair<ll,ll>;
const ll INF=1LL<<30;
const ll LINF=1LL<<60;
const double eps=1e-9;
const ll MOD=1000000007LL;
template<typename T>void chmin(T &a,T b){a=min(a,b);};
template<typename T>void chmax(T &a,T b){a=max(a,b);};
template<typename T>vector<T> make_v(size_t a){return vector<T>(a);}
template<typename T,typename... Ts>auto make_v(size_t a,Ts... ts){return vector<decltype(make_v<T>(ts...))>(a,make_v<T>(ts...));}
template<typename T,typename V>typename enable_if<is_class<T>::value==0>::type fill_v(T& t,const V& v){t=v;}
template<typename T,typename V>typename enable_if<is_class<T>::value!=0>::type fill_v(T& t,const V& v){for(auto &e:t)fill_v(e,v);};
int dx[4]={0,1,0,-1};
int dy[4]={1,0,-1,0};
int main(){
	ll n;cin>>n;
	vector<P> v(n);
	for(int i=0;i<n;i++){
		cin>>v[i].second>>v[i].first;
	}
	sort(all(v));
	reverse(all(v));
	auto dp=make_v<ll>(n+10,n+10);
	fill_v(dp,LINF);
	dp[0][0]=0;
	for(ll i=1;i<=n;i++){
		for(ll j=0;j<=min(i,n/3);j++){
			if(j){
				chmin(dp[i][j],dp[i-1][j-1]);
			}
			if(j<i)chmin(dp[i][j],dp[i-1][j]+v[i-1].second+v[i-1].first*(i-j-1LL));
		}
	}
	cout<<dp[n][n/3]<<endl;
}