The Function $\displaystyle z=f(x,y)=11x+12y$

Constraints: (>=greater or equal to, >=less than or equal to)

$\displaystyle x>0$,

$\displaystyle y>0$,

$\displaystyle x+y>11$,

$\displaystyle y<x+12$,

$\displaystyle y<14$,

$\displaystyle x-y<11$

What are the corner points? I don't even know where to begin