#include <bits/stdc++.h> using namespace std; #define int long long #define pb push_back #define fi first #define se second #define FOR(i,n) for(int i = 0;i<n;i++) #define rep(i,s,n) for(int i = s;i<n;i++) #define rrep(i,s,n) for(int i = (n)-1;i>=(s);i--) #define all(v) (v).begin(),(v).end() #define chmin(a,b) a=min((a),(b)) #define chmax(a,b) a=max((a),(b)) #define endl '\n' #define IOS() ios_base::sync_with_stdio(0);cin.tie(0) typedef long long ll; typedef pair<int,int>pint; typedef vector<int>vint; typedef vector<pint>vpint; const ll MOD=1000000007,INF=1ll<<60; int dx[]={0,0,1,-1}; int dy[]={-1,1,0,0}; typedef pair<pint,int>P1; typedef vector<vint>vvint; int dp[2020][2020]; signed main() { IOS(); int N; cin>>N; vint a(N),b(N); vpint v(N); rep(i,0,N){ cin>>a[i]>>b[i]; v[i]={b[i],a[i]}; } sort(all(v)); reverse(all(v)); rep(i,0,2020)rep(j,0,2020)dp[i][j]=INF; dp[0][0]=0; rep(i,0,N){ rep(j,0,N){ if(dp[i][j]==INF)continue; chmin(dp[i+1][j+1],dp[i][j]+v[i].se+v[i].fi*j); chmin(dp[i+1][j],dp[i][j]); } } cout<<dp[N][N-N/3]<<endl; return 0; }