Integer block sample

Title description

Given is a positive integer N. Find the value

.

Here, for a real number x, [x] denotes the largest integer not exceeding x.

Constraints
1≤N≤1012
 
N is an integer.

Enter

Input is given from Standard Input in the following format:

N

Output

Print the answer.

Sample input Copy

【Example 1】3【Example 2】10000000000

Sample output Copy

【Example 1】5【Example 2】231802823220

Tips

Example 1 Explanation:
We have

.

Example 2 Explanation:
Note that the input and output may not fit into a 32-bit integer type.

#includeusing namespace std;typedef long long ll;typedef double db;ll n,sum,r;int main(){ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);cin>>n;for(ll l=1;l<=n;l=r+1){r=n/(n/l);sum+=(r-l+1)*(n/l);}cout<