using System;

public class Program

{

    static void z1(){

        int[] arr = {2, 3, 4, 5};

        int proizv=1;

        foreach(var i in arr)

            proizv *= i;

        Console.WriteLine(proizv);

    }

    static void z2(){

        int[] arr = new int[11];

        Random rnd = new Random();

        int sum=0;

        for(int i=0; i<11; i++)

            arr[i] = rnd.Next(-5, 6);

        foreach(var i in arr)

            Console.Write(i+" ");

        Console.WriteLine();

        foreach(var i in arr){

            if(i>0)

                sum += i;

        }

        Console.WriteLine(sum);

    }

    static void z3(){

        int[] arr = {10, 20, 30, 50, 235, 3000, 22, 57, 10, 111111, 425, 2666, 11, 1, 2, 5};

        int[] arr1 = new int[arr.Length];

        int value;

        int index=0;

        int indexarr=0;

        Console.Write("индексы : ");

        foreach(var i in arr){

            value = i;

            while(value >= 10){

                value /= 10;

            }

            if(value==1 || value==2 || value==5){

                arr1[index++] = i;

                Console.Write(indexarr+" ");

            }

            indexarr++;

        }

        Console.WriteLine();

        Console.Write("числа начинающиеся на 1, 2, 5 : ");

        foreach(var i in arr1){

            if(i==0)

                break;

            Console.Write(i+" ");

        }

    }

    static void z4kalendar(){

        int[,,] mesaci = new [6,7];

    }

    public static void Main()

    {

        z3();

    }

}