P1929 [CF2038K] Grid Walk
提高
题目描述

You have an $n \times n$ grid and two integers $a$ and $b$. Both the rows and the columns are numbered from $1$ to $n$. Let's denote the cell at the intersection of the $i$-th row and the $j$-th column as $(i, j)$.

You are standing in the cell $(1, 1)$ and want to move into the cell $(n, n)$.

Suppose you are in the cell $(i, j)$; in one step, you can move either into the cell $(i, j + 1)$ or into the cell $(i + 1, j)$ if the corresponding cells exist.

Let's define the cost of the cell $(i, j)$ as $c(i, j) = \gcd(i, a) + \gcd(j, b)$ (here, $\gcd(x,y)$ denotes the greatest common divisor of $x$ and $y$). The cost of the route from $(1, 1)$ to $(n, n)$ is the sum of costs of the visited cells (including the starting cell and the finishing cell).

Find the route with minimum possible cost and print its cost.

Input

The only line contains three integers $n$, $a$, and $b$ ($2 \le n \le 10^6$; $1 \le a, b \le 10^6$).

Output

Print one integer — the cost of the cheapest route from $(1, 1)$ to $(n, n)$.

输入格式

见题面 Input 部分

输出格式

见题面 Output 部分

样例输入
4 2 4
样例输出
21
提示

The first example is described in the picture above.