#include <iostream>

 #include <cstdio>

 #include <cstring>

 #include <algorithm>

 #include <cstdlib>

 using namespace std;

 const int INF = <<;

 struct node

 {

     int u;

     int v;

     int w;

     int next;

 }edge[];

 int dis[];

 int mi,ma,n;

 void bellman_ford()

 {

    int i,f=;

    while(f)

    {

        f=;

        for(i=; i<=n; i++)

        if(dis[edge[i].u]>dis[edge[i].v]-edge[i].w)

        {

            dis[edge[i].u]=dis[edge[i].v]-edge[i].w;

            f=;

        }

        for(i=mi; i<=ma; i++)

        if(dis[i]>dis[i-]+)

        {

            dis[i]=dis[i-]+;

            f=;

        }

        for(i=ma; i>=mi; i--)

        if(dis[i-]>dis[i])

        {

            dis[i-]=dis[i];

            f=;

        }

    }

 }

 int main()

 {

     int i;

     while(~scanf("%d",&n))

     {

         mi=INF;  ma=-;

         for(i=; i<=n; i++)

         {

             scanf("%d%d%d",&edge[i].u, &edge[i].v, &edge[i].w);

             if(mi>edge[i].u)

             mi=edge[i].u;

             if(ma<edge[i].v)

             ma=edge[i].v;

             edge[i].u--;

             dis[i]=;

         }

         bellman_ford();

        printf("%d\n",dis[ma]-dis[mi-]);

     }

     return ;

 }