using System;

using System.Linq;

public class Program

{

    public static void Main()

    {

        const char wildcard = '?';

        var c1 = "INPUT,1,1,0,0,0,0,0,0,0,0,0,0";

        var c2 = "INPUT,?,?,1,?,?,?,?,?,?,?,?,?";

        var index = c1.Zip(c2, (a, b) => new { a, b })

            .Select((p, i) => new { p.a, p.b, i })

            .Where(p => p.b != wildcard)

            .FirstOrDefault(p => p.a != p.b)?.i;

        Console.WriteLine(index);

    }

}