using System;

public class Program

{

    public static void Main()

    {

        //var dNo = "010096016403230606250000030002100000000000";

        //var dec = Convert.ToDouble(dNo);

        var  sIp = "x...o.x...o";

        //sIp = "xxx...xxx";

        var fCar = 'x';

        var sCar = 'o';

        var distance = -1;

        var fcarIn = 0;

        var scarIn = 0;

        for(var i=0;i<sIp.Length;i++)

        {

            if(sIp[i]==fCar)

                fcarIn=i;

            if(sIp[i]==sCar)

                scarIn=i;

            if(fcarIn!=0&&scarIn!=0)

            {

                var dif = Math.Abs(fcarIn-scarIn);

                if(distance==-1)

                    distance = dif;

                distance = distance>dif?dif:distance;

            }

        }

        Console.WriteLine(distance);    

    }

}