using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApp1
{
    class Program
    {
        static void Feladat1()
        {
            int[] a = { 9, 7, 3, 5, 4, 2, 6 };
            int n = a.Length;
            int[] b = new int[n];
            int j = 0;
            for (int i = 0; i < n; ++i)
                if (a[i] < 5)
                {
                    b[j] = a[i];
                    ++j;
                }
            Console.WriteLine("Eredeti: ");
            for (int i = 0; i < n; ++i)
                Console.WriteLine($"{a[i]} ");
            Console.WriteLine("");
            Console.WriteLine("Kivlogatott: ");
            for (int i = 0; i < j; ++i)
                Console.WriteLine($"{b[i]} ");
            Console.WriteLine("");
        }

        public static int Lineariskereses(int[] tomb, int elem)
        {
            int index = -1;
            for (int i = 0; i < tomb.Length; ++i)
            {
                if (tomb[i] == elem)
                {
                    index = i;
                    break;
                }
            }
            return index;
        }
        static void Feladat2()
        {
            int[] a = { 9, 7, 3, 5, 4, 2, 6 };
            int elem = Convert.ToInt32(Console.ReadLine());
            Console.WriteLine(Lineariskereses(a,elem));
        }
        static void Main(string[] args)
        {
            Feladat2();
            Console.ReadKey();
        }
    }
}