def gridChallenge(grid):
    # Sort each row
    for idx in range(len(grid)):
        strList = list(grid[idx])
        strList.sort()
        grid[idx] = "".join(strList)
    # Join all grid list to a single string
    strJoin = "".join(grid)
    gLength = len(grid)
		# Create the column list based on grid length
    reverseGrid = [0] * len(grid)
    for i in range(len(strJoin)):
		    # get the ascii code
        curr = ord(strJoin[i])
				# Get the saved grid ascii code based on index % length
        prev = reverseGrid[i % gLength]
        diff = curr - prev
				# if the diff < 0, means current ascii value less than previous, which means it's not in order
        if diff < 0:
            return "NO"

        reverseGrid[i % gLength] = curr
    return "YES"