Cod sursa(job #905484)

Utilizator fred1fred fred fred1 Data 5 martie 2013 21:15:30
Problema Fractii Scor 30
Compilator cpp Status done
Runda Arhiva de probleme Marime 0.34 kb
Raporteaza aceasta sursa 
using namespace std;
#include<fstream>
ifstream fin("fractii.in");
ofstream fout("fractii.out");
int S,i,v[1000005],j,n;
int main()
{
	fin>>n;
	for(i=2;i<=n;i++)
		v[i]=i;
	for(i=2;i<=n;i++)
	{
		if(v[i]==i)
		{
			for(j=i;j<=n;j=j+i)
				v[j]=v[j]/i*(i-1);
		}
	}
	for(i=2;i<=n;i++)
		S=S+v[i];
	fout<<2*S+1;
	return 0;
}