From Wikipedia:

In modular arithmetic,   the modular multiplicative inverse of an integer    a    modulo    m    is an integer    x    such that





a

x
≡
1


(
mod

m
)

.


{\displaystyle a\,x\equiv 1{\pmod {m}}.}


Or in other words, such that:





∃
k
∈

Z

,

a

x
=
1
+
k

m


{\displaystyle \exists k\in \mathbb {Z} ,\qquad a\,x=1+k\,m}


It can be shown that such an inverse exists   if and only if    a    and    m    are coprime,   but we will ignore this for this task.



Task

Either by implementing the algorithm, by using a dedicated library or by using a built-in function in
your language,   compute the modular inverse of   42 modulo 2017.




Print FUNC(_MulInv(42, 2017))
End
 
_MulInv Param(2)
  Local(5)
 
  c@ = b@
  f@ = 0
  g@ = 1
 
  If b@ = 1 Then Return
 
  Do While a@ > 1
    e@ = a@ / b@
    d@ = b@
    b@ = a@ % b@
    a@ = d@
 
    d@ = f@
    f@ = g@ - e@ * f@
    g@ = d@
  Loop
 
  If g@ < 0 Then g@ = g@ + c@
Return (g@)