Cod sursa(job #2984269)
Utilizator | Data | 23 februarie 2023 20:01:30 | |
---|---|---|---|
Problema | Fractii | Scor | 100 |
Compilator | cpp-64 | Status | done |
Runda | Arhiva de probleme | Marime | 0.5 kb |
#include <fstream>
using namespace std;
ifstream fin("fractii.in");
ofstream fout("fractii.out");
int e[1000001], i, j, n;
unsigned long long rasp;
int main()
{
fin>>n;
for(i=1; i<=n; ++i) e[i] = i;
for(i=2; i<=n; ++i)
if(e[i] == i ){
--e[i];
for(j=2; i*j<=n; ++j)
e[i*j] = e[i*j] / i * (i-1);
}
rasp=n;
for(i=2; i<=n; ++i)
rasp = rasp + 1ll * (1 + 2*(e[i]-1));
fout<<rasp;
return 0;
}