Cod sursa(job #983175)

Utilizator AeroHHorea Stefan AeroH Data 11 august 2013 00:24:36
Problema Fractii Scor 100
Compilator cpp Status done
Runda Arhiva de probleme Marime 0.34 kb
Raporteaza aceasta sursa 
#include <fstream>
#define ll long long int
using namespace std;
ifstream cin("fractii.in");
ofstream cout("fractii.out");
int i,j,n;
ll rasp;
int v[1000001];
int main()
{
cin>>n;v[1]=1;
for(i=2;i<=n;++i)
v[i]=i-1;
for(i=2;2*i<=n;++i)
for(j=2*i;j<=n;j+=i)
v[j]-=v[i];
for (i=1;i<=n;++i) rasp+=v[i];
cout<<(rasp<<1)-1;
return 0;
}