using System;

namespace y
{
    class Program
    {
        static void Main(string[] args)
        {
            var ss = Console.ReadLine().Split();
            long a = long.Parse(ss[0]);
            long b = long.Parse(ss[1]);
            long c = long.Parse(ss[2]);
            long ans = 999999999999999999;


            for (int i = 17; i >= 0; i--)
            {
                long n = ans;
                for (int j = 0; j < 10; j++)
                {
                    if (j >= 1) n -= (long)Math.Pow(10, i);
                    if (n / a * b + (n - n / a) >= c)
                    {
                        ans = n;
                    }
                }
            }

            if (ans == 999999999999999999 && ans / a * b + (ans - ans / a) < c)
            {
                ans = 1000000000000000000;
            }

            Console.WriteLine(ans);
        }
    }
}