STOCK-BASED COMPENSATION - Assumptions (Details) - $ / shares	3 Months Ended	9 Months Ended	12 Months Ended
Oct. 31, 2018	Oct. 31, 2019	Oct. 31, 2018	Jan. 31, 2019	Jan. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award
Grant date fair value of stock options granted		$ 0.44
Expected term in years		4 years		4 years
Minimum
Share-based Compensation Arrangement by Share-based Payment Award
Expected volatility	78.80%	68.30%	78.80%	78.80%	83.90%
Expected term in years	4 years		4 years		6 years
Risk-free interest rate	2.72%	1.88%	2.72%	2.43%	1.80%
Maximum
Share-based Compensation Arrangement by Share-based Payment Award
Expected volatility	91.00%	70.80%	91.00%	91.00%	96.80%
Expected term in years	8 years 7 months 6 days		8 years 7 months 6 days		9 years 4 months 21 days
Risk-free interest rate	3.10%	2.51%	3.10%	2.98%	2.70%

The estimated measure of the percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period.

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- Definition

The risk-free interest rate assumption that is used in valuing an option on its own shares.

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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No definition available.

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- Definition

The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.

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- Definition

Expected term of share-based compensation awards, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (f)(2)(i)
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-Publisher FASB
-Name Accounting Standards Codification
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-Subparagraph (SAB Topic 14.D.2)
-URI http://asc.fasb.org/extlink&oid=115993241&loc=d3e301413-122809

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