Cod sursa(job #350289)
Utilizator | Data | 23 septembrie 2009 12:14:10 | |
---|---|---|---|
Problema | Fractii | Scor | 100 |
Compilator | cpp | Status | done |
Runda | Arhiva de probleme | Marime | 0.36 kb |
#include<stdio.h>
long n,e[1000001];
long long ss;
int main()
{
long i,j;
freopen("fractii.in","r",stdin);
freopen("fractii.out","w",stdout);
scanf("%ld",&n);
for(i=2;i<=n;++i)
e[i]=i;
for(i=2;i<=n;++i)
if(e[i]==i)
for(j=i;j<=n;j+=i)
e[j]=e[j]/i*(i-1);
ss=0;
for(i=2;i<=n;++i)
ss+=e[i];
printf("%lld",ss*2+1);
return 0;
}