Cod sursa(job #1284698)
Utilizator | Data | 6 decembrie 2014 19:14:18 | |
---|---|---|---|
Problema | Fractii | Scor | 100 |
Compilator | cpp | Status | done |
Runda | Arhiva de probleme | Marime | 0.46 kb |
#include <cstdio>
#define ll long long
#define VL 1000005
using namespace std;
ll k;
int n,i,j;
int v[VL];
void val()
{
freopen("fractii.in","r",stdin);
freopen("fractii.out","w",stdout);
scanf("%d",&n);
for(i=2;i<=n;++i)
v[i]=i-1;
}
int main()
{
val();
for(i=2;i<=n;++i)
{
for(j=2*i;j<=n;j+=i)
v[j]-=v[i];
k+=v[i];
}
k=k*2+1;
printf("%lld\n",k);
return 0;
}