学步园

#include<iostream>
#include<cstdio>
#define LL long long
using namespace std;
inline LL phi(int n){ 
	if(n==1)return 1;  
	LL ans=1; 
    for(LL i=2;i*i<=n;i++) 
        if(n%i==0){ 
            int k=0; 
            while(n%i==0)k++,n/=i; 
            ans*=i-1; 
            for(int j=2;j<=k;j++)ans*=i;        
    	} 
    if(n>1)ans*=n-1; 
    return ans; 
} 
int n;
long long ans;
int main(){
	scanf("%d",&n);
	for(int i=1;i*i<=n;i++)
		if(n%i==0){
			ans+=(long long)i*phi(n/i);
			if(i*i<n)ans+=(long long)n/i*phi(i);
		}
	printf("%lld",ans);
	return 0;
}