print multInv(42, 2017)
end
function multInv(a,b)
x0 = 0
b0 = b
multInv = 1
if b = 1 then return
while a > 1
q = a / b
t = b
b = a mod b
a = t
t = x0
x0 = multInv - q * x0
multInv = int(t)
end while
if multInv < 0 then return multInv + b0
end function