Two identical symmetric double convex lenses of focal length f are cut into two equal parts L_1, L_2 by AB plane and L_3, L_4 by XY plane as shown in…

Two identical symmetric double convex lenses of focal length $\displaystyle f$ are cut into two equal parts $\displaystyle \mathrm{L}_1, \mathrm{~L}_2$ by AB plane and $\displaystyle \mathrm{L}_3, \mathrm{~L}_4$ by XY plane as shown in figure respectively. The ratio of focal lengths of lenses $\displaystyle \mathrm{L}_1$ and $\displaystyle \mathrm{L}_3$ is