def gridChallenge(grid):
    sorted_grid = ["".join(sorted(row)) for row in grid]
    num_cols = len(sorted_grid[0])
    num_rows = len(sorted_grid)
    
    for col_idx in range(num_cols):
        columns = []
        for row_idx in range(num_rows):
            columns.append(sorted_grid[row_idx][col_idx])
       
        if columns != sorted(columns):
            return "NO"
    return "YES"