Cod sursa(job #1893603)

Utilizator smatei16Matei Staicu smatei16 Data 25 februarie 2017 20:15:10
Problema Fractii Scor 30
Compilator cpp Status done
Runda Arhiva de probleme Marime 0.31 kb
Raporteaza aceasta sursa 
#include <cstdio>

using namespace std;
int n,a[1000003],i,j;
long long s;
int main()
{freopen("fractii.in","r",stdin);
freopen("fractii.out","w",stdout);
scanf("%d",&n);
for(i=1;i<=n;i++)
a[i]=i-1;
for(i=1;i<=n;i++){
s+=a[i];
for(j=i+i;j<=n;j+=i)a[j]-=a[i];
}
printf("%d",2*s+1);

    return 0;
}