I - Painting a Square

SDUT 2022 Spring Team Contest(for 21) - 15 - Virtual Judge

There is a square of size a times aa×a. In its top left corner there is a square brush of size b times bb×b. You should use this brush to paint a square (you can assume that the top left corner of size b times bb×b is already painted). It is allowed to move a brush only in parallel to the square's sides. What is the minimal distance the center of the brush should pass to make the whole square painted?

Input

The input contains two integers aa and bb (1 le b le a le 10^{6}1≤b≤a≤106) — the sides of the square and the brush, correspondingly.

Output

Output a single integer — the minimal distance that should be passed by the center of the brush. It is guaranteed that the answer is an integer.

Sample 1

4 2

6

Sample 2

4 3

3

Sample 3

9 3

24

Sample 4

1000000 1

999999999999

题解：分析可得红色矩阵应当螺旋移动才能使得步数最少，而给定矩阵边长相同，在纸上模拟直接找到规律即可。

#include
using namespace std;
typedef long long ll;
int main()
{
    int a,b;
    scanf("%d %d",&a,&b);
    ll tmp=a-b;
    ll ans=tmp;//初始是tmp，因为开始必须要走3个tmp，后面只用走2个
    while(tmp>0)
    {
        ans=ans+tmp+tmp;
        tmp-=b;
    }
    printf("%lldn",ans);
    return 0;
}