Write a C program to find the slope of line through the two points $($x$1,$y$1)$ and $($x$2,$y$2).$ The

formula is given : m $=($y$2-$ y$1)/($x$2-$ x$1)$

Declaration: x$1,$y$1,$ x$2,$ y$2,$ and m should be float variables $($not integer$).$

Make sure that check: If x$1$ equals x$2,$ then the line is vertical, and the slope is undefined. If the slope is undefined, it should write a message $$Slope undefined$.$