Cod sursa(job #520085)

Utilizator alexdmotocMotoc Alexandru alexdmotoc Data 7 ianuarie 2011 13:28:33
Problema Fractii Scor 100
Compilator cpp Status done
Runda Arhiva de probleme Marime 0.33 kb
Raporteaza aceasta sursa 
#include<iostream>
#include<fstream>
using namespace std;

long long n,s=0,a[1000001],i,j;


int main()
{
	ifstream f("fractii.in");
	ofstream g("fractii.out");
	
	
	f>>n;

	for(i=2; i<=n;i++)
		a[i]=i-1;
	
	for(i=2;i<=n;i++)
	{
		for(j=2;j*i<=n;j++)
			a[j*i]=a[j*i]-a[i];
	s=s+a[i];
	}
	g<<s*2+1;
	return 0;
}