Nuclear fusion is a reaction in which atomic nuclei merge to form the nucleus of a new atom. The mass of the new atom’s nucleus is lower than the sum of the merging nuclei’s masses, a difference that is released as energy. This is, for instance, the reaction that occurs in the Sun. The energy released during fusion can be calculated by the equation $E=\Delta m\cdot c^2$, where $\Delta \text{m}$ is the difference between the initial and final masses in the reaction, and $c$ is the speed of light. When calculating the aforementioned energy, nucleus mass can be conveniently quantified using the atomic mass unit $(u)$, which is roughly equivalent to $900\text{MeV}(1\text{u}\to 900\text{MeV})$. Consider the hypothetical nuclear fusion reaction:

$${}^{222}X+{}^{4}Y\to {}^{221}Z$$

Note that the masses of ${}^{222}X$, ${}^{4}Y$, and ${}^{221}Z$ are $222\text{u}$, $4\text{u}$, and $221\text{u}$, respectively. The amount of energy released in this reaction is