use std::ops::{Mul, Add};
use std::iter::Product;
use std::ops::RangeInclusive;


fn factorial_iterative<T, Out>(m: T, n: T) -> Out
where
    T: Product, RangeInclusive<T>: Iterator<Item = T>,
    Out: Product, Mul<T, Output=Out> + Add<T, Output=Out>
{
    let ret = (m..=n).product();
    return ret;
}

fn main()
{

}