一条街的一边有几座房子。因为环保原因居民想要在路边种些树，路边的地区被分割成块，并被编号成1..N，每个部分为一个单位尺寸大小并最多可种一棵树，每个居民想在门前种些树并指定了三个号码B,E,T，这三个数表示该居民想在B和E之间最少种T棵树。当

然，B≤E,居民必须记住在指定区不能种多于区域地块数的树，所以T≤E-B+l。居民们想

种树的各自区域可以交叉。你的任务是求出能满足所有要求的最少的树的数量。

-One side of the street there are several houses. Because of environmental reasons people want to plant some trees on the roadside, roadside area is divided into blocks, and was number into 1 .. N, each part of a unit size and up to plant a tree, each resident want to plant some trees in front and specifies three numbers B, E, T, which means that residents want three numbers in between B and E at least kind of T tree. Of course, B ≤ E, residents must remember that in the designated area can not grow more than the number of tree plots area, so T ≤ E-B+l. Residents who want to plant trees in their respective regions can overlap. Your task is to find the minimum required to meet all of the number of trees.