In a Young's double slit experiment, slits are separated by

In a Young's double slit experiment, slits are separated by $0.5 \mathrm{~mm}$, and the screen is placed $150 \mathrm{~cm}$ away. A beam of light consisting of two wavelengths, $650 \mathrm{~nm}$ and $520 \mathrm{~nm}$, is used to obtain interference fringes on the screen. The least distance from the common central maximum to the point where the bright fringes due to both the wavelengths coincide is :-