using System;

​

namespace ConsoleApp1

{

    class Program

    {

        static void Main(string[] args)

        {

            int N;

            Console.WriteLine("Nhap N: ");

            N = int.Parse(Console.ReadLine());

​

            int i = 1;

            int Tong = 0;

            while (N / i >= 1)

            {

                Tong = Tong + 1;

                i = i * 10;

            }

            Console.WriteLine("Ket qua la " + Tong);

​

        }

    }

}

​