long[] ids = Array.ConvertAll(Console.ReadLine().Trim().Split(' '), idsTemp => Convert.ToInt64(idsTemp))
        ;

static int findShortest(int graphNodes, int[] graphFrom, int[] graphTo, long[] ids, int val)
{
    // solve here
    Dictionary<int, HashSet<int>> Adj = new Dictionary<int, HashSet<int>>();
    for(int i=1; i <= graphNodes; i++)
        Adj[i] = new HashSet<int>();

    for(int i=0; i<graphFrom.Length; i++)
    {
        Adj[graphFrom[i]].Add(graphTo[i]);
        Adj[graphTo[i]].Add(graphFrom[i]);
    }

    HashSet<int> requiredNodes = new HashSet<int>();
    Dictionary<int, int> distanceTo = new Dictionary<int, int>();

    for(int i=1; i<=graphNodes; i++)
        if(ids[i-1] == val)
            requiredNodes.Add(i);

    Queue<int> q;
    int minimumDistance = int.MaxValue;
    int distance;
    foreach(int node in requiredNodes)
    {
        q = new Queue<int>();
        distanceTo = new Dictionary<int, int>();
        distance = 1;
        q.Enqueue(node);
        distanceTo[node] = 0;

        while(q.Count != 0)
        {
            int cur = q.Dequeue();
            foreach(int n in Adj[cur])
            {
                if(!distanceTo.ContainsKey(n))
                {
                    q.Enqueue(n);
                    distanceTo[n] = distance;
                }
            }
            distance++;
            foreach(var n in requiredNodes.Where(a => a != cur && a != node))
                if(distanceTo.ContainsKey(n))
                    if(distanceTo[n]<minimumDistance)
                        minimumDistance = distanceTo[n];
        }
    }

    if(minimumDistance == int.MaxValue)
        return -1;
    else
        return minimumDistance;
}