Pagini recente » Istoria paginii runda/oji_bv_1112/clasament | Cod sursa (job #3275425) | Cod sursa (job #147096) | Cod sursa (job #61236) | Cod sursa (job #229450)
Cod sursa(job #229450)
#include <cstdio>
#include <bitset>
using namespace std;
bitset<2000001> ciur;
int main() {
freopen("ciur.in", "r", stdin);
freopen("ciur.out", "w", stdout);
int n;
scanf("%d", &n);
int cnt = 0;
for (int i = 2; i <= n; ++i) if (!ciur[i]) {
cnt++;
for (int j = i << 1; j <= n; j+=i) ciur[j] = 1;
}
printf("%d\n", cnt);
return 0;
}