Problem on Riemann Integration: $f(x)=\frac{1}{n}$ for $\frac1n>x\geq \frac{1}{n+1}$.
Obtain the value of $\int_0^1f(x) \ dx$, where $f(x) = \begin{cases} \frac {1}{n}, & \frac{1}{n+1}<x\le\frac{1}{n}\\ 0, & x=0 \end{cases}$