Vectors in Space · Easy problem

Vectors $\mathbf u$ and $\mathbf v$ have $\lVert \mathbf u \rVert = 2$, $\lVert \mathbf v \rVert = 3$ and $\mathbf u \cdot \mathbf v = 3$. Find the angle between $\mathbf u$ and $\mathbf v$, in radians.