procedure main(args)
    a := integer(args[1]) | 42
    b := integer(args[2]) | 2017
    write(mul_inv(a,b))
end

procedure mul_inv(a,b)
    if b == 1 then return 1
    (b0 := b, x0 := 0, x1 := 1)
    while a > 1 do {
        q := a/b
        (t := b, b := a%b, a := t)
        (t := x0, x0 := x1-q*x0, x1 := t)
        }
    return if (x1 > 0) then x1 else x1+b0
end