Triangles $ABC$ and $DEF$ are graphed in the $xy$-plane. Triangle $ABC$ has vertices $A,B,$ and $C$ at $(1,1),(1,4),$ and $(4,1),$ respectively. Triangle $DEF$ has vertices $D,E,$ and $F$ at $(1,1),(1,4+p),$ and $(4+p,1),$ respectively, where $p$ is a positive constant. If the measure of $\angle B$ is $x^{\circ },$ what is the measure of $\angle F$ ?