#include<bits/stdc++.h>
#define ll long long
#define N 505
using namespace std;
const ll inf=1e18;
int px[N],py[N],n;
ll f[N][N],mn[N][N];
int main(){
	ios::sync_with_stdio(0);
	cin>>n;
	for(int i=1;i<=n;++i)cin>>px[i]>>py[i];
	for(int i=1;i<=n;++i){
		int mnx=1e9,mny=1e9;
		for(int j=i;j<=n;++j){
			mnx=min(mnx,px[j]),mny=min(mny,py[j]);
			mn[i][j]=1ll*mnx+1ll*mny,f[i][j]=inf;
		}
	}
	for(int i=n;i;--i)
		for(int j=i;j<=n;++j){
			if(i==j)continue;f[i][j]=inf;
			for(int k=i;k<j;++k)f[i][j]=min(f[i][j],f[i][k]+f[k+1][j]+mn[i][k]+mn[k+1][j]-2ll*mn[i][j]);
		}
	cout<<f[1][n]+mn[1][n];
	return 0;
}