Cod sursa(job #283692)

Utilizator xbladeIagar Robert xblade Data 19 martie 2009 15:59:29
Problema Fractii Scor 30
Compilator cpp Status done
Runda Arhiva de probleme Marime 0.29 kb
Raporteaza aceasta sursa 
#include<fstream.h>
#define N 1000001
ifstream in("fractii.in");
ofstream out("fractii.out");
long long n,a[N];
int main()
{
	in>>n;
	long i,j,c=0;
	for(i=1;i<=n;i++)
		a[i]=i-1;
	for(i=1;i<=n;i++)
	{
		for(j=2*i;j<=n;j+=i)
			a[j]=a[j]-a[i];
		c+=a[i];
	}
	out<<c*2+1;
	return 0;
}