Cod sursa(job #940061)
Utilizator | skyper skyper96 | Data | 15 aprilie 2013 16:02:23 |
---|---|---|---|
Problema | Fractii | Scor | 100 |
Compilator | cpp | Status | done |
Runda | Arhiva de probleme | Marime | 0.47 kb |
#include<fstream>
#define N 1000005
using namespace std;
ifstream fin("fractii.in");
ofstream fout("fractii.out");
int n,v[N];
long long sol;
void solve()
{
for(int i=1;i<=n;i++)
v[i]=i-1;
for(int i=2;i<=n;i++)
for(int j=i+i;j<=n;j+=i)
v[j]-=v[i];
for(int i=2;i<=n;i++)
sol+=v[i];
sol=sol*2+1;
}
int main()
{
fin>>n;
solve();
fout<<sol<<'\n';
fin.close();
fout.close();
return 0;
}