Cod sursa(job #2268011)
Utilizator | Data | 24 octombrie 2018 14:14:14 | |
---|---|---|---|
Problema | Fractii | Scor | 100 |
Compilator | cpp-64 | Status | done |
Runda | Arhiva de probleme | Marime | 0.5 kb |
#include <fstream>
using namespace std;
ifstream in("fractii.in");
ofstream out("fractii.out");
int v[1000005];
void ciur( int n )
{
for ( int i = 2; i <= n; i ++ )
v[i] = i;
for ( int i = 2; i <= n; i ++ )
if ( v[i] == i )
for ( int j = i; j <= n; j += i )
v[j] = v[j] / i * ( i - 1 );
}
int main()
{
long long x, s=0 , i;
in>> x;
ciur (x) ;
for(i=0; i<= x; i++)
s += v[i];
out<< s*2+1 ;
return 0;
}