using System;

​

public class Program

{

    public static void Main()

    {

        Console.WriteLine(NbYear(1500, 5, 100, 5000));

        Console.WriteLine(NbYear(1500000, 2.5, 10000, 2000000));

        Console.WriteLine(NbYear(1500000, 0.25, 1000, 2000000));

    }

​

    public static int NbYear(int p0, double percent, int aug, int p)

    {

        // population increase throughout years

        for(int i = 1;;i++)

        {

            p0 = (int)Math.Floor(p0 * (100+percent) / 100) + aug;

            if(p0>=p) return i;

        }

        //int yearCount = 0;

        //while (p0 < p)

        //{

        //  p0 = (int)Math.Floor(p0 * (100+percent) / 100) + aug;

        //  yearCount++;

        //}

        //return yearCount;

    }

}