In the figure shown three slits `s_(1),s_(2)` and `s_(3)` are illuminated with of wavelength `lambda.lambda ltltd` and `D gtgt d.` Each slit prouduces same intensity `I` on the screen. If intensity at the point on screen directly infront of `s_(2)` is `3I` then the maximum value of `lambda` is `(nd^(2))/(2D)` Find value of `n.`