Cod sursa(job #107461)
Utilizator | Paicu Alexandru rethos | Data | 19 noiembrie 2007 21:14:15 |
---|---|---|---|
Problema | Fractii | Scor | 10 |
Compilator | cpp | Status | done |
Runda | Arhiva de probleme | Marime | 0.47 kb |
#include <fstream.h>
int prim[1000];
long long erast (long long x)
{ long long nr,i,j;
for (i=1;i<=x;i++) prim[i]=0;
for (i=2;i<x;i++)
if (x%i==0)
{ for (j=i;j<=x;j=j+i)
prim[j]=1;
}
nr=0;
for (i=1;i<x;i++)
if (prim[i]==0) nr++;
return nr;
}
int main()
{ long long n,i,j,nr;
ifstream f("fractii.in");
f>>n;
f.close();
nr=1;
for (i=2;i<=n;i++)
nr+=2*erast(i);
ofstream g("fractii.out");
g<<nr;
g.close();
return 0;
}