题目描述

blablabla

样例

blablabla

算法1

.

include[HTML_REMOVED]

using namespace std;
int main ()
{
int a,b,s;
cin>>a>>b;
cout<<a+b<<endl;
return 0;
}

题目描述

blablabla

样例

blablabla

算法1

include[HTML_REMOVED]

using namespace std;
long long n,phi[10000010],s[10000010]={},primes[10000010],cnt=0;
bool st[10000010]={false};

long long ol(int n)
{
phi[1]=1;
for(int i=2;i<=n;i) {
if(!st[i]){
primes[cnt]=i;
phi[i]=i-1;
}
for(int j=0;primes[j]<=n/i;j){
st[primes[j]i]=true;
if(i%primes[j]==0){
phi[primes[j]i]=phi[i]primes[j];
break;
}
phi[primes[j]i]=phi[i]*(primes[j]-1);
}
}
for(int i=2;i<=n;i){
s[i]=s[i-1]+phi[i];

}

}
int main()
{
cin>>n;
ol(n);
long long res=0;
for(int i=0;i<cnt;i++){
int p=primes[i];
res+=s[n/p] *2+1;
}
cout<<res;
return 0;
}