def solve():
    n, d = map(int, input().split())
    if d == 1:
        print(n - 1)
        return
    elif d % n == 0:
        print(n // d - 1)
        return

    visited = set([])
    now, ans = 0, 0
    while True:
        visited |= set([now])
        t = now
        now = (n - (n % d) + d) % n
        ans += ((n - t) // d + 1) if (n - t) % d != 0 else (n - t) // d
        # print(visited, now, ans)
        if now in visited:
            ans -= 1
            break
    print(ans)


if __name__=="__main__":
    solve()