4.1
#include <iostream>
using namespace std;
int main()
{
        setlocale(0, "");
        int n, sum=0, a;
        cin >> n;
        if (n>0)
        {
        for (int i = 0; i <= n; i++)
        {
            a = i*i;
            sum += a;
        }
        cout << sum;
        system("pause");
        }
        if (n<0)
        {
            cout<<"Bang bang"<<endl;
        }
        return 0;
}
4.2
#include <iostream>
using namespace std;
int main()
{
        setlocale(0, "");
        int n, sum=0;
        cin >> n;
        if (n>0)
        {
        for (int i = 0; i <= n)
        {
            sum+=i;
            i+=2;
        }
        cout << sum;
        system("pause");
        }
        else if(n<0)
            for(int i=-1; i<=0)
            {
                sum+=i;
                i-=2;
            }

            return 0;
}