Inverse in $\mathbb {Z}$/p$\mathbb {Z}$ : inv inverse or /

To compute the inverse of an integer n in $\mathbb {Z}$/p$\mathbb {Z}$, input 1/n%p or inv(n%p) or inverse(n%p).
Input :

inv(3%13)

Output :

-4%13

Indeed 3× -4 = - 12 = 1 ( mod 13).