[AHOI 2005]COMMON 约数研究

Description

Input

只有一行一个整数 N（0 < N < 1000000）。

Output

只有一行输出，为整数M，即f(1)到f(N)的累加和。

Sample Input

3

Sample Output

5

题解

水题一道...做不出的要$AFO$了...

 //It is made by Awson on 2017.11.10
 #include <map>
 #include <set>
 #include <cmath>
 #include <ctime>
 #include <queue>
 #include <stack>
 #include <cstdio>
 #include <string>
 #include <vector>
 #include <cstdlib>
 #include <cstring>
 #include <iostream>
 #include <algorithm>
 #define LL long long
 #define LD long double
 #define Max(a, b) ((a) > (b) ? (a) : (b))
 #define Min(a, b) ((a) < (b) ? (a) : (b))
 #define sqr(x) ((x)*(x))
 #define y1 yy
 #define count COUNT
 #define Lr(o) (o<<1)
 #define Rr(o) (o<<1|1)
 using namespace std;
 const int N = ;

 int n;
 LL ans;

 void work() {
     scanf("%d", &n);
     for (int i = ; i <= n; i++)
     ans += n/i;
     printf("%lld\n", ans);
 }
 int main() {
     work();
     return ;
 }