Input and output not recognized and missing \endcsname in algorithm

I want to write an algorithm, and I have the code segment shown below, but it provides multiple errors, such as input and output commands are not recognized and I get missing \endcsname error. Additionally, the line numbers are not inserted, any idea how to fix all the errors and also insert the line numbers?

\documentclass[a4paper]{paper}
\usepackage{amsmath}
\usepackage{amssymb}

\usepackage{algorithm}
\usepackage{algpseudocode}

\begin{document}

\begin{algorithm}[H]
\Input{A vector \textbf{a}}
\Output{Bit reversed vector}
    \Function{NTT}{$\textbf{a}$}
        \State $m \gets 1$
        \State $k \gets n / 2$
        \While{$m < n$}
            \For {$i = 0$ \To $m - 1$}
                \State $jFirst \gets 2 \cdot i \cdot k$
                \State $jLast \gets jFirst + k - 1$
                \State $S \gets \psi_{rev}[m + i]$
                \For {$j = jFirst$ \To $jLast$}
                    \State $l \gets j + k$
                    \State $t \gets \textbf{a}[j]$
                    \State $u \gets \textbf{a}[l] \cdot S$
                    \State $\textbf{a}[j] \gets t + u \mod q$
                    \State $\textbf{a}[l] \gets t - u \mod q$
                \EndFor
            \EndFor
            \State $m \gets m \cdot 2$
            \State $k \gets n / 2$
        \EndWhile
        \State \Return $\textbf{a}$
    \EndFunction
    \caption{Cooley-Tukey (CT) Forward NTT}
    \label{CTAlgo}
\end{algorithm}

\end{document}