1706 求合数和

#include<cstdio>
#include<cstring>
#include<iostream>
using namespace std;
#define N 10010
int prime[N];
bool check[N];
int main()
{
    memset(check,0,sizeof check);
    int tot=0;
    int n,sum=0;
    scanf("%d",&n); 
    for(int i=2;i<=n;i++){
       if(!check[i])
         prime[tot++]=i;
       for(int j=0;j<tot;j++){
            if(i*prime[j]>n) break;
            check[i*prime[j]]=1;
            if(i%prime[j]==0) break;
          }
      }
    for(int i=2;i<=n;i++)
        if(check[i]) sum+=i;
    printf("%d\n",sum);             
    return 0;
}