Cod sursa(job #285462)

Utilizator lolopolololopolo lolopolo Data 22 martie 2009 16:55:48
Problema Fractii Scor 100
Compilator cpp Status done
Runda Arhiva de probleme Marime 0.34 kb
Raporteaza aceasta sursa 
#include <stdio.h>
long n,i,j;
double nr;
long x[1000001];

int main()
{
	freopen("fractii.in","rt",stdin);
	freopen("fractii.out","wt",stdout);
	scanf("%ld",&n);
	for (i=2;i<=n;i++) x[i]=i-1;
	for (i=2;i<=n>>1;i++)
		for (j=i+i;j<=n;j+=i)
			x[j]-=x[i];
	nr=0;
	for (i=2;i<=n;i++) nr+=x[i]<<1;
	printf("%.0f\n",nr+1);
	return 0;
}