using System;
using static System.Console;
using System.Linq;
using System.Collections.Generic;
class Program
{
    static int NN => int.Parse(ReadLine());
    static int[] NList => ReadLine().Split().Select(int.Parse).ToArray();
    static string[] SList(long n) => Enumerable.Repeat(0, (int)n).Select(_ => ReadLine()).ToArray();
    public static void Main()
    {
        Solve();
    }
    static void Solve()
    {
        var p = NList;
        var ans = 0;
        if (p[2] % p[0] == 0 && p[2] <= p[1])
        {
            WriteLine(p[2] / p[0]);
            ++ans;
        }
        if ((p[1] + p[2]) % p[0] == 0)
        {
            WriteLine((p[1] + p[2]) / p[0]);
            ++ans;
        }
        if (ans == 0)
        {
            WriteLine(-1);
        }
    }
}