Cod sursa(job #1760155)
Utilizator | Data | 20 septembrie 2016 13:43:22 | |
---|---|---|---|
Problema | Sum | Scor | 0 |
Compilator | cpp | Status | done |
Runda | Arhiva de probleme | Marime | 0.37 kb |
#include<fstream>
#include<algorithm>
using namespace std;
ifstream fin("sum.in");
ofstream fout("sum.out");
int a[200002];
long long s;
int main()
{
long long n,m=0,i,j;
fin>>n;
for(i=1;i<=2*n;i++)
s+=i;
for(i=2;i<=n;i++)
if(!a[i])
{if(n%i==0){a[i]=0;
for(j=i+i;j<=2*n;j+=i)
a[j]=1;}
}for(i=1;i<=2*n;i++)
if(a[i])
s-=i;
fout<<s;}