Step 1: Understand the meaning of a monic polynomial.
A polynomial is called monic if its leading coefficient is equal to \(1\).
Step 2: Identify the leading term.
The given polynomial is
\[
f(x)=a_nx^n+a_{n-1}x^{n-1}+\cdots+a_1x+a_0
\]
Here, the highest power of \(x\) is
\[
x^n
\]
So the leading term is
\[
a_nx^n
\]
Therefore, the leading coefficient is
\[
a_n
\]
Step 3: Apply the condition for a monic polynomial.
Since \(f(x)\) is monic, its leading coefficient must be \(1\).
Hence,
\[
a_n=1
\]
Step 4: Final conclusion.
Therefore,
\[
\boxed{a_n=1}
\]