hdu6024

#include<cstdio>
#include<iostream>
#include<algorithm>
using namespace std;
typedef long long ll;
const int maxn = 3010;
const ll INF = 1e9;
int pos[maxn], cost[maxn];
ll dp[maxn][2];


int main()
{
    int n;
    while(cin >> n)
    {
        for(int i = 1; i <= n; i++)
            dp[i][0] = dp[i][1] = 2 * INF;

        for(int i = 1; i <= n; i++)
        {
            scanf("%d%d", &pos[i], &cost[i]);
        }

        dp[1][1] = cost[1];

        for(int i = 2; i <= n; i++)
        {
            dp[i][1] = min(dp[i - 1][0], dp[i - 1][1]) + cost[i];       //第i个建造糖果屋

            dp[i][0] = dp[i - 1][1] + pos[i] - pos[i - 1];　　　　　　　　//第i个不建造糖果屋，向前找到接在哪个糖果屋后面建造总花费最小
            ll sum = pos[i] - pos[i - 1];
            int k = 1;
            for(int j = i - 1; j >= 2; j--)
            {
                sum += (pos[j] - pos[j - 1]) * (++k);
                dp[i][0] = min(dp[i][0], dp[j - 1][1] + sum);
            }
            /*
            ll pre;
            for(int j = 1; j < i; j++)
            {
                if(dp[j][1] != 2 * INF)
                    pre = j;
            }
            dp[i][0] = pos[i] - pos[pre] + dp[pre][1];　　　　错误
            dp[i][1] = cost[i] + min(dp[i - 1][1], dp[i - 1][0]);
            */
        }
        cout << min(dp[n][0], dp[n][1]) << endl;
    }
    return 0;
}