Cod sursa(job #2546812)
Utilizator | Data | 14 februarie 2020 16:25:35 | |
---|---|---|---|
Problema | Ciurul lui Eratosthenes | Scor | 30 |
Compilator | cpp-64 | Status | done |
Runda | Arhiva educationala | Marime | 0.41 kb |
#include <iostream>
#include <fstream>
using namespace std;
ifstream fin("ciur.in");
ofstream fout("ciur.out");
inline bool prim(int x)
{
if(x<2) return 0;
if((x%2)==0 && x>2) return 0;
for(int d=3;d*d<=x;d+=2)
if((x%d)==0) return 0;
return 1;
}
int main()
{
int n,cnt=0;
fin>>n;
for(int i=1;i<=n;i++)
if(prim(i))
cnt++;
fout<<cnt;
}