You are given an array routes representing bus routes where routes[i] is a bus route that the ith bus repeats forever. For example, if routes[1] = [1, 5, 7], this means that the 1st bus travels in the sequence 1 -> 5 -> 7 -> 1 -> 5 -> 7 -> 1 -> ... forever. You will start at the bus stop source (You are not on any bus initially), and you want to go to the bus stop target. You can travel between bus stops by buses only. Return the least number of buses you must take to travel from source to target. Return -1 if it is not possible.
Input Format
Input is already handled for you.
Output Format
return theleast number of buses you need to take.
Constraints
1 <= routes.length <= 500. 1 <= routes[i].length <= 10^5. All the values of routes[i] are unique. 0 <= routes[i][j] < 10^6. 0 <= source, target < 10^6.
Example
Input
2 3 1 2 7 3 6 7 1 6
Output
2