Last Correlation

Question

Let $X_1,\dots, X_n$ be random variables such that it's known $\corr{X_i}{X_j} = 0$ for all $i < j$, except the pair $(i,j) = (1,n)$. What are the possible values of $\rho = \corr{X_1}{X_n}$ when $n = 50$? If the possible correlations are an interval $[a,b]$, report $b-a$. If there is only one possible correlation $\rho$, report $\rho$.