Cod sursa(job #547380)
Utilizator | Botocan Bogdan Rengel | Data | 6 martie 2011 12:06:39 |
---|---|---|---|
Problema | Ciurul lui Eratosthenes | Scor | 30 |
Compilator | cpp | Status | done |
Runda | Arhiva educationala | Marime | 0.29 kb |
#include<cstdio>
char a[2000001];
int n,i,j,k;
int main(){
freopen("ciur.in","r",stdin);
freopen("ciur.out","w",stdout);
scanf("%d",&n);
for(i=2;i<=n;i++)
for(j=2*i;j<=n;j+=i)
a[j]=1;
for(i=2;i<=n;i++)
if(!a[i]) k++;
printf("%d",k);
return 0;
}