Oscillations and Waves: JEE Main 2021 Physics question

A closed organ pipe of length L and an open organ pipe contain gases of densities $\rho$₁ and $\rho$₂ respectively. The compressibility of gases are equal in both the pipes. Both the pipes are vibrating in their first overtone with same frequency. The length of the open pipe is ${x \over 3}L\sqrt {{{{\rho _1}} \over {{\rho _2}}}}$ where x is ___________. (Round off to the Nearest Integer)