Let R be a rectangle that is the union of a finite number of rectangles Ri, 1≤i≤n, satisfying the following conditions:
(i) The sides of every rectangle Ri are parallel to the sides of R.
(ii) The interiors of any two different rectangles Ri are disjoint.
(iii) Each rectangle Ri has at least one side of integral length.
Prove that R has at least one side of integral length.
Variant: Same problem but with rectangular parallelepipeds having at least one integral side. geometryrectanglecalculusintegrationnumber theoryIMO Shortlist