use std::iter::Sum;

pub struct M {
	i : i32
}

#[derive(Debug)]
pub struct N {
	k : i32
}

impl Sum for M {
	fn sum<I : Iterator<Item = M>>(_iter : I) -> M {
		M { i : 32 }
	}
}

impl<M> Sum<M> for N {
	fn sum<I : Iterator<Item = M >>(_iter : I) -> N {
		N { k : 1 }
	}
}

fn main() {
	let a : Vec<M> = vec![M { i : 3 }];
	let x = a.iter().sum::<N>();
	println!("{:?}", x);
}