#nullable enable

#region
var (_input, _iter) = (Array.Empty<string>(), 0);
T I<T>() where T : IParsable<T>
{
    while (_iter >= _input.Length) (_input, _iter) = (Console.ReadLine()!.Split(' '), 0);
    return T.Parse(_input[_iter++], null);
}
#endregion

static T[] Range<T>(int n, Func<T> F) => Enumerable.Range(0, n).Select(_ => F()).ToArray();

var n = I<int>();
var a = I<int>();
var b = I<int>();
var kz = Range(n + 1, I<long>);

decimal F(int x)
{
    decimal res = 0;
    decimal xp = 1;
    for (var i = 0; i <= n; i++)
    {
        xp *= x;
        res += xp * kz[i] / (i + 1);
    }
    return res;
}

decimal eps = 1;
for (var i = 0; i < 10; i++) eps /= 10;
var ans = (long)(F(b) - F(a) + eps);
Console.WriteLine(ans);