Cod sursa(job #293774)

Utilizator StigmaSimina Pitur Stigma Data 2 aprilie 2009 03:58:53
Problema Fractii Scor 100
Compilator cpp Status done
Runda Arhiva de probleme Marime 0.34 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-1;

c[1]=1;

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

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