#include #include #include using namespace std; int main () { unsigned long long x; int a; cout << "Enter a number:"; cin >> x; unsigned long long i = (x-1); for (i=x; i>1; --i/*--*/) { if (x%i==0 && x!=i) { cout << "Not prime!" << endl; a=1700; break; return 3; } } if (a!=1700) cout << "Prime!" << endl; return 0; }