Cod sursa(job #293775)

Utilizator StigmaSimina Pitur Stigma Data 2 aprilie 2009 04:05:43
Problema Fractii Scor 100
Compilator cpp Status done
Runda Arhiva de probleme Marime 0.35 kb
Raporteaza aceasta sursa 
#include <fstream.h>
#define dim 1000005
ifstream fin("fractii.in");
ofstream fout("fractii.out");

long long S,n,c[dim];


int main()
{long long i,j;
fin>>n; 

for (i=1;i<=n;i++)
	 c[i]=i;


for (i=2;i<=n;i++)
	if(c[i]==i)
	for (j=i;j<=n;j+=i) c[j]=c[j]/i*(i-1);

for (i=1;i<=n;i++) S+=c[i];
	
fout<<S*2-1;
fout.close();
return 0;
}