Yes, you're right I must have had the two confused when I made this. I just fixed it, thanks for letting us know!

In Rust 1.15.1, the function signature currently is

fn max_product(mut lst: Vec<u32>, n_largest_elements: i32) -> u32 {
    return 0;
}

However, an element of input could be less than zero, lst should be Vec<i32> instead of Vec<u32>. And the same issue for the return type. Please check it if possible.