AtCoder Regular Contest 102 C

 这题纯脑残了 分奇偶处理一下就行了 

链接 ：https://atcoder.jp/contests/arc102/tasks/arc102_a

#include<bits/stdc++.h>
#define rep(i,a,n) for(int i=a;i<=n;++i)
#define per(i,a,n) for(int i=n;i>=a;--i)
#define pb push_back
#define fi first
#define se second
#define io std::ios::sync_with_stdio(false)
using namespace std;
typedef long long ll;
typedef pair<int,int> pii;
const int P = 1e9+7, INF = 0x3f3f3f3f;
const int maxn=1e5+50;
ll gcd(ll a,ll b)
{
    return b?gcd(b,a%b):a;
}
ll qpow(ll a,ll n)
{
    ll r=1%P;
    for (a%=P; n; a=a*a%P,n>>=1)if(n&1)r=r*a%P;
    return r;
}

 int main()
 {
   int n,k;
   cin>>n>>k;
   ll ans=n/k;
   ans=ans*ans*ans;
   if(k%2==0)
   {
       n-=k/2;
       if(n>=0)
       {
       ll  x=n/k+1;
       ans+=x*x*x;
     }
   }
   cout<<ans<<endl;
 }