#include <iostream>
#include <cstdlib>
using namespace std;
int main() {
int n;
cout << "Num: ";
cin >> n;
int arr[n + 1];
for (int &i:arr) {
i = 1;
}
for (int k = 2; k*k <= n; k++) {
if (arr[k] == 1) {
for (int i = k * k; i <= n; i += k) {
arr[i] = 0;
}
}
}
if (arr[n] == 1) {
cout << "Prime number";
}
else {
cout << "Composite number";
}
return 0;
Простой
