/**************************************************************    Problem: 4805    User: BeiYu    Language: C++    Result: Accepted    Time:1100 ms    Memory:48172 kb****************************************************************/ #include <bits/stdc++.h>using namespace std; typedef long long ll;typedef long double ld;const int N = 2000050;const ll p = 1000000007; ll Pow(ll a,ll b,ll r=1) { for(;b;b>>=1,a=a*a%p) if(b&1) r=r*a%p;return r; }ll mul(ll a,ll b) { return (a*b-((ll)((ld)a/p*b+1e-3))*p+p)%p; } int b[N],pr[N],cp;ll phi[N],sp[N],inv2=Pow(2,p-2); void pre(int n) {    for(int i=2;i<=n;i++) {        if(!b[i]) pr[++cp]=i,phi[i]=i-1;        for(int j=1;j<=cp && i*pr[j]<=n;j++) {            b[i*pr[j]]=1;            if(i%pr[j]) phi[i*pr[j]]=phi[i]*(pr[j]-1);            else { phi[i*pr[j]]=phi[i]*pr[j];break; }        }    }phi[1]=1;    for(int i=1;i<=n;i++) sp[i]=(sp[i-1]+phi[i]);}map<ll,ll> mp;ll S(ll n) {    if(n<=2000000) return sp[n];    if(mp.count(n)) return mp[n];    ll fn;    if(n&1) fn=n*((n+1)>>1);    else fn=(n>>1)*(n+1);    for(ll i=2,j;i<=n;i=j+1) {        j=n/(n/i);        fn=(fn-(j-i+1)*S(n/i));    }return mp[n]=fn;} int main() {    pre(2000000);    ll n;    scanf("%lld",&n);    printf("%lld\n",S(n));    return 0;}