Pagini recente » Cod sursa (job #2377224) | Borderou de evaluare (job #3226072) | Diferente pentru dot-com/2009/solutii/runda-1 intre reviziile 5 si 7 | Drumuri Lungi | Cod sursa (job #2033893)
#include <fstream>
using namespace std;
ifstream fi("fractii.in");
ofstream fo("fractii.out");
long long n,i,j,s;
int PI[1000001];
int main()
{
fi>>n;
for(i=1;i<=n;i++)
PI[i]=i-1;
PI[1]=1;
for(i=2;i<=n;i++)
for(j=2*i;j<=n;j+=i)
PI[j]-=PI[i];
for(i=1;i<=n;i++)
s+=PI[i];
fo<<s*2-1;
fi.close();
fo.close();
return 0;
}