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| #include <bits/stdc++.h>
using namespace std;
const double eps = 1e-10;
const double pi = 3.1415926535897932384626433832795;
const double eln = 2.718281828459045235360287471352;
#define f(i, a, b) for (int i = a; i <= b; i++)
#define scan(x) scanf("%d", &x)
#define mp make_pair
#define pb push_back
#define lowbit(x) (x&(-x))
#define fi first
#define se second
#define SZ(x) int((x).size())
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define summ(a) (accumulate(all(a), 0ll))
typedef unsigned long long ull;
typedef pair<int,int> pii;
typedef vector<int> vi;
using ll=long long;
const int maxn=1e6+9;
ll tt=1e6,a,b,c,d,k,mu[maxn],s[maxn],pr[maxn],cnt,ans;
bitset<(int)1e7+9>vis;
void init(int x){
mu[1]=1;
for(ll i=2;i<=x;++i){
if(!vis[i])pr[++cnt]=i,mu[i]=-1;
for(int j=1;j<=cnt&&i*pr[j]<=x;++j){
vis[pr[j]*i]=1;
if(i%pr[j]==0)break;
mu[i*pr[j]]=-mu[i];
}
}
for(int i=1;i<=x;++i)s[i]=s[i-1]+mu[i];
}
ll cal(ll x,ll y){
x/=k,y/=k;
if(x>y)swap(x,y);
ll res=0;
for(ll l=1,r;l<=x;l=r+1){
r=min(x/(x/l),y/(y/l));
res+=(x/l)*(y/l)*(s[r]-s[l-1]);
}
return res;
}
int main()
{
ios::sync_with_stdio(false);
cin.tie(0);
init(tt);
cin>>a>>b>>k;
cout<<cal(a,b);
return 0;
}
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