傳送門

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