{1,1},{1,2},{1,2},{2,3},{2,3},{3,4},{3,4},{3,5},{3,5},{4,6},{4,6},{5,7},{5,7},{7,9},{7,9},{8,10},{8,10},{-1,-1},{-1,-1},{-1,-1},{15,17},{17,19},{19,21},{21,23},{23,25}