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 \gt 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 \le n \le 1000) - amount of employees in the company. The following line contains n space-separated numbers qj (0 \le qj \le 106)- the employees' qualifications. The following line contains number m (0 \le m \le 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 \le ai,bi \le n, 0 \le ci \le 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 \gt qbi.

Output the only line - the minimum cost of building such a hierarchy, or -1 if it is impossible to build it.

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.