show that exists exactly one n such that $\gamma_1$ is homotopic to $\gamma_2 = e^{2\pi int}$

Question

Let $\gamma_1 $ be a closed path in $\Bbb{C}\setminus0$ such that $0 \in int (\gamma_1)$

show that exists exactly one $n \in \Bbb{Z}\setminus 0$ such that $\gamma_1$ is homotopic to $\gamma_2 : [0,1] \to \{z: |z| = 1\} \quad \gamma_2 = e^{2\pi int}$