Cod sursa(job #3219119)
Utilizator | Ceclan Tudor Tudor28 | Data | 30 martie 2024 10:07:50 |
---|---|---|---|
Problema | Fractii | Scor | 100 |
Compilator | cpp-64 | Status | done |
Runda | Arhiva de probleme | Marime | 0.59 kb |
#include <bits/stdc++.h>
using namespace std;
ifstream fin("fractii.in");
ofstream fout("fractii.out");
const int NMAX =1000001;
int phi[NMAX+1];
void euler()
{
for(int i=1; i<NMAX; i++)
phi[i]=i;
for(int i=2; i<NMAX; i++)
{
if(phi[i]==i)
{
for(int j=i; j<NMAX; j+=i)
{
phi[j]=phi[j]/i*(i-1);
}
}
}
}
int main()
{
euler();
int n;
long long total=0;
fin>>n;
for(int i=2;i<=n;i++){
total+=phi[i];
}
fout<<total*2+1;
return 0;
}