Cod sursa(job #2499171)
Utilizator | Urzica Radu-Bogdan bijien | Data | 25 noiembrie 2019 16:39:15 |
---|---|---|---|
Problema | Fractii | Scor | 100 |
Compilator | cpp-64 | Status | done |
Runda | Arhiva de probleme | Marime | 0.48 kb |
#include <bits/stdc++.h>
using namespace std;
ifstream f("fractii.in");
ofstream g("fractii.out");
int n;
int a[1000001];
void refresh(int x)
{
int i;
for(i=x; i<=n; i+=x)
{
a[i]/=x;
a[i]*=(x-1);
}
}
int main()
{
f>>n;
int i;
for(i=1; i<=n; i++)
a[i]=i;
for(i=2; i<=n; i++)
if(a[i]==i)
refresh(i);
long long s=1;
for(i=2; i<=n; i++)
s+=2*a[i];
g<<s;
return 0;
}