Rectangle

You are given a grid with $N$ rows and $M$ columns, where each cell contains either '0' or '1'. Find out whether all the cells containing '1'-s form a rectangle, I.e, is there a rectangular contiguous subgrid such that every cell within it is a '1', and all the cells containing '1'-s are within this subgrid. ### Input - The first line of the input contains a single integer $T$ denoting the numb