Mai intai trebuie sa te autentifici.
Cod sursa(job #577072)
| Utilizator |  Plesa Mihail Iulian mihai.plesa |
Data | 9 aprilie 2011 18:29:13 |
|---|---|---|---|
| Problema | Fractii | Scor | 100 |
| Compilator | cpp | Status | done |
| Runda | Arhiva de probleme | Marime | 0.32 kb |
#include<fstream>
using namespace std;
ifstream fin("fractii.in");
ofstream fout("fractii.out");
long a[1000100],n,i,j;
long long suma;
int main()
{fin>>n;;
for(i=1;i<=n;i++)
a[i]=i;
for(i=2;i<=n;i++)
if(a[i]==i)
for(j=i;j<=n;j+=i)
a[j]=a[j]/i*(i-1);
for(i=2;i<=n;++i)
suma=suma+a[i];
fout<<2*suma+1;
return 0;
}