Cod sursa(job #1017723)
Utilizator | Dan Claudiu DiClau | Data | 28 octombrie 2013 10:12:38 |
---|---|---|---|
Problema | Fractii | Scor | 30 |
Compilator | cpp | Status | done |
Runda | Arhiva de probleme | Marime | 0.54 kb |
#include <stdio.h>
using namespace std;
int e[1000001];
int main() {
FILE *in,*out;
in=fopen("fractii.in","r");
out=fopen("fractii.out","w");
int n,i,j;
fscanf(in,"%d",&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);
}
long long c=0;
for (i=2;i<=n;i++)
{
c=c+e[i];
}
c=c*2;
c=c+1;
fprintf(out,"%d",c);
return 0;
}