Statistics and Probability: JEE Main 2021 Mathematics question

Let X₁, X₂, ......., X₁₈ be eighteen observations such that $\sum\limits_{i = 1}^{18} {({X_i} - } \alpha ) = 36$ and $\sum\limits_{i = 1}^{18} {({X_i} - } \beta {)^2} = 90$, where $\alpha$ and $\beta$ are distinct real numbers. If the standard deviation of these observations is 1, then the value of | $\alpha$ $-$ $\beta$ | is ____________.