#include <iostream>
#include <cstdio>
#include <cmath>
#include <cstdlib>
#include <cstring>

using namespace std;

int n,t1,t2;
int f[401][401];
int sum[401][401];
int main()
{
	freopen("book.in","r",stdin);
	freopen("book.out","w",stdout);
	scanf("%d",&n);
	for (int i=1;i<=n;i++)
	{
		scanf("%d%d",&t1,&t2);
		sum[i][1]=t1-t2;
	}
	for (int j=2;j<=n;j++)
	for (int i=1;i<=n-i+1;i++)
	{
		f[i][j]=2000000000;
		sum[i][j]=sum[i][1]+sum[i+1][j-1];
		for (int k=1;k<=j-1;k++)
		{
			if (f[i][j]>f[i][k]+f[i+k][j-k]+sum[i][k]+sum[i+k][j-k]) f[i][j]=f[i][k]+f[i+k][j-k]+sum[i][k]+sum[i+k][j-k];
		}
	}
	printf("%d\n",f[1][n]);
}