You have m workers numbered 1 through m, and you have n tasks that must be completed. You know which tasks can be performed by each of the workers. If worker i completes t different tasks, he must be paid cost[i]*t2. You would like to minimize the total cost of completing all the tasks.
You will be given a String can describing the capabilities of your workers. The i-th element describes worker i and contains n characters. The j-th character is 'Y' if the worker can perform the j-th task, and 'N' if he can't. You will also be given a int cost. The i-th element of cost is the cost of worker i (as used in the formula above). All indices are 1-based. Return the minimal total cost required to complete all the tasks, or -1 if all the tasks cannot be completed.