If $z_1=2-i$ and $z_2=1+i$$,$ then $\left|\frac{z_1+z_2+1}{z_1-z_2+i}\right|$ is

Let $z_1$ and $z_2$ be complex numbers satisfying $\left|z_1\right|=\left|z_2\right|=2$ and $\left|z_1+z_2\right|=3$. Then $\left|\frac{1}{z_1}+\frac{1}{z_2}\right|=$