Nick's company employed n people. Now Nick needs to build a tree hierarchy of «supervisor-surbodinate» relations in the company (this is to say that each employee, except one, has exactly one supervisor). There are m applications written in the following form: «employee ai is ready to become a supervisor of employee bi at extra cost ci». The qualification qj of each employee is known, and for each application the following is true: qai>qbi.
Would you help Nick calculate the minimum cost of such a hierarchy, or find out that it is impossible to build it.
The first input line contains integer n (1≤n≤1000) − amount of employees in the company. The following line contains n space-separated numbers qj (0≤qj≤106)− the employees' qualifications. The following line contains number m (0≤m≤10000) − amount of received applications. The following m lines contain the applications themselves, each of them in the form of three space-separated numbers: ai, bi and ci (1≤ai,bi≤n, 0≤ci≤106). Different applications can be similar, i.e. they can come from one and the same employee who offered to become a supervisor of the same person but at a different cost. For each application qai>qbi.
Output the only line − the minimum cost of building such a hierarchy, or -1 if it is impossible to build it.
4
7 2 3 1
4
1 2 5
2 4 1
3 4 1
1 3 5
11
3
1 2 3
2
3 1 2
3 1 3
-1
In the first sample one of the possible ways for building a hierarchy is to take applications with indexes 1, 2 and 4, which give 11 as the minimum total cost. In the second sample it is impossible to build the required hierarchy, so the answer is -1.