Cod sursa(job #365823)
Utilizator | Data | 20 noiembrie 2009 00:17:44 | |
---|---|---|---|
Problema | Ciurul lui Eratosthenes | Scor | 30 |
Compilator | cpp | Status | done |
Runda | Arhiva educationala | Marime | 0.49 kb |
#include <cstdio>
#include <math.h>
using namespace std;
int main()
{
int n,ct=0;
bool prim;
freopen("ciur.in","r",stdin);
freopen("ciur.out","w",stdout);
scanf("%d",&n);
if (n>=1)
ct++;
//printf("%d ",1);
if (n>=2)
ct++;
//printf("%d ",2);
if (n>2)
for (int i=3;i<=n;i=i+2)
{
prim=true;
for (int j=2;j<=sqrt(i)&&prim;j++)
if (i%j==0)
prim=false;
if (prim)
ct++;
//printf("%d ",i);
}
printf("%d\n",ct-1);
return 0;
}