, and let f : E2 → Ed for d ≥ 2 be a function such that for every p, q ∈ E2 if p − q = c, then f(p) − f(q) ≤ c, and if p − q = s, then f(p) − f(q) ≥ s. Then f is a congruence. This result depends on and expands a result of Rdo et. al. [9], where a similar result holds, but for