我想问一下，接下来的主函数怎么写

#include
using namespace std;
bool even(long num){
if (num % 2 == 0)
return true;
else
return false;
}
int main() {
double long num;
cin >> num;

cout << "是不是偶数" << num << endl;


return 0;

}

#include <iostream>
using namespace std;
bool even(long num)
{
    if (num % 2 == 0)
        return true;
    else
        return false;
}
int main()
{
    double long num;
    cin >> num;
    if(even(num)){
        cout << num << "是偶数"  << endl;
    }else{
        cout << num << "不是偶数" << endl;
    }
    return 0;
}