using System;
using System.Linq;

class Scanner
{
    string[] s;
    int i;
    char[] cs = new char[] { ' ' };
    public Scanner()
    {
        s = new string[0];
        i = 0;
    }

    public string Next()
    {
        if (i < s.Length) return s[i++];
        string st = Console.ReadLine();
        while (st == "") st = Console.ReadLine();
        s = st.Split(cs, StringSplitOptions.RemoveEmptyEntries);
        if (s.Length == 0) return Next();
        i = 0;
        return s[i++];
    }

    public int NextInt()
    {
        return int.Parse(Next());
    }

    public long NextLong()
    {
        return long.Parse(Next());
    }
}

class Program
{

    static void Main(string[] args)
    {
        // Comment

        var scanner = new Scanner();

        long A = scanner.NextLong();
        long B = scanner.NextLong();
        long C = scanner.NextLong();

        bool exist = false;

        for (long i = 1 ; i < 1000000 ; i++){

            long X = A * i;
            if (X-B > 0) X -= B;
            if (X == C){
                Console.WriteLine(i);
                exist = true;
            }

        }

        if (!exist){
            Console.WriteLine(-1);
        }

        /*
        for (int lp = 0 ; lp < T ; lp++){

            int[] li = Console.ReadLine().Split(' ').Select(int.Parse).ToArray();

            int L = li[0];
            int R = li[1];
            int A = li[2];
            int B = li[3];

            int ans;
            if ( A*L+B > A*R+B ){
                ans = A*L+B;
            }else{
                ans = A*R+B;
            }

            Console.WriteLine(ans);

        }*/

    }
}