Cod sursa(job #2849009)
Utilizator | Mihai Blidaru qMihai | Data | 14 februarie 2022 12:54:13 |
---|---|---|---|
Problema | Fructe | Scor | 0 |
Compilator | cpp-64 | Status | done |
Runda | Arhiva de probleme | Marime | 0.43 kb |
#include <fstream>
using namespace std;
int main()
{
unsigned i, n, phi[999999];
unsigned long long x = 0;
ifstream fin("fractii.in");
ofstream fout("fractii.out");
fin>> n;
for (i = 2; i <= n;phi[i]=i, ++i);
for (i = 2; i <= n; ++i)
if (phi[i] == i)
for (unsigned j = i; j <= n; phi[j] /= i,phi[j]*=i - 1,j+=i);
for (i = 2; i <= n; x+=phi[i++]*2);
fout << x + 1;
}