Find the maximum and minimum values of the expression $\displaystyle P=\frac{a-b}{c} +\frac{b-c}{a} +\frac{c-a}{b}$. Where $\displaystyle a,b,c$ are positive real numbers satisfying the condition $\displaystyle min\left \{ a,b,c \right \}\geq \frac{1}{4}max\left \{ a,b,c \right \}$