import std.stdio;

void main()
{
    writeln("Enter a number:");
    int input;
    readf("%d", &input);
    writeln("Factorial:", factorial(input));
}

int factorial(int n)
{
    if (n <= 1)
        return 1;
    return n * factorial(n - 1);
}

Options: Vala, Crystal, D, Nim

Use the following link to guess an answer, answer + results posted in 12 hours. (If you say the answer in the replies please put it in spoiler tags)

https://strawpoll.com/Qrgebk7PKZp