Cod sursa(job #3217706)
Utilizator | Tone Alexandru tonealexandru | Data | 24 martie 2024 13:31:12 |
---|---|---|---|
Problema | Fractii | Scor | 0 |
Compilator | cpp-64 | Status | done |
Runda | Arhiva de probleme | Marime | 0.58 kb |
#include <bits/stdc++.h>
#define int long long
using namespace std;
int euler[100005];
void phi(int n)
{
for(int i=2;i<=n;i++)
euler[i]=i;
for(int i=2;i<=n;i++)
{
if(euler[i]==i)
for(int j=i;j<=n;j+=i)
euler[j]=euler[j]/i*(i-1);
}
}
int32_t main()
{
ifstream cin("fractii.in");
ofstream cout("fractii.out");
int n, suma=0;
cin>>n;
phi(n);
for(int i=1;i<=n;i++)
{
if(i<=n/2)
suma+=2*euler[i];
else
suma+=euler[i];
}
cout<<(suma-n+1)*2+1;
return 0;
}