I want a little help with this question
$$ \int\_{-\pi /4}^{n\pi -\pi /4} \left | sinx + cosx \right |dx $$

I tried to solve it by using the fact that since the following function is periodic with given period $\pi $ then we can say the integral is similar to the following - 
$n\int\_{0}^{\pi} \left | sinx + cosx \right |dx $ then evaluated considering proper sign of the modulus function, but the answer is wrong. Where am I making the mistake?