Chemistry Question from JEE Main 2023 · 13 April, Shift 2

See the following chemical reaction: $Cr_2O_7^{2-} + XH^+ + 6Fe^{2+} \rightarrow YCr^{3+} + 6Fe^{3+} + ZH_2O$ The sum of $X$, $Y$ and $Z$ is _____ .