【SDOI2008】仪仗队

//裸的欧拉函数
//y=kx
//求不同的k有多少
#include<bits/stdc++.h>
#define ll long long
#define N 40010
using namespace std;
ll f[N],n,ans;
inline ll read(){
    char ch;
    bool f=false;
    ll res=;
    while (((ch=getchar())<''||ch>'')&&ch!='-');
    if (ch=='-')
        f=true;
    else
        res=ch-'';
    while ((ch=getchar())>=''&&ch<='')
        res=(res<<)+(res<<)+ch-'';
    return f?~res+:res;
}
int main(){
    n=read();
    if (n==){
        printf("0\n");
        return ;
    }
    for (int i=;i<=n;i++)
        f[i]=i;
    for (int i=;i<=n;i++)
        if (f[i]==i)
            for (int j=i;j<=n;j+=i)
                f[j]=f[j]/i*(i-);
    ans=;
    for(int i=;i<n;++i)
        ans+=f[i]*;
    printf("%lld\n",ans+);
    return ;
}