#include #include #include using namespace std; int main () { unsigned long long x; cout << "Enter a number:"; cin >> x; unsigned long long i = (x-1); int a; for (i=x; i>1; --i) { if (x%i==0 && x!=i) { cout << "Not prime!" << endl; a=1; break; return 3; } } if (a!=1) cout << "Prime!" << endl; return 2; }