Let a=p^2 q^3 r^n and b=p^3 q^m r^2, where p, q, r are prime numbers. If LCM of a and b is p^3 q^4 r^3, then the value of 3 n-2 m is

Let $\displaystyle a=p^{2} q^{3} r^{n}$ and $\displaystyle b=p^{3} q^{m} r^{2}$, where $\displaystyle p, q, r$ are prime numbers. If LCM of a and b is $\displaystyle p^{3} q^{4} r^{3}$, then the value of $\displaystyle 3 n-2 m$ is