# Leibnitz-rule and multiple integrals … again

I have a following integral

$\frac{d}{dx}\int\limits_0^x\int\limits_0^{x-x_1}\int\limits_0^{x-x_1-x_2}(x-x_1-x_2-x_3)e^{-(x-x_1-x_2-x_3)^m}dx_3dx_2dx_1$.

It easily gives itself for the simplification, but the Leibnitz-rule someway doesn't work for me. Has anybody any suggestion/idea?

Regards, Hz