Sum and Average of unspecified number of values in C++

#include <iostream>
#include <vector>
using namespace std ;
int main()
{
    int n,i,n_p,n_n,total=0;
    float av;
    vector<int>n1;
    cout<<"Enter integers , The input ends if it is 0 : ";
    cin>>n;
    if (n==0)
    {
        cout<<"You haven't entered any number just 0";
    }
    else
    {
        for(i=0;n!=0;i++)
        {
            n1.push_back(n);
            cin>>n;
        }
        for (auto i = n1.begin(); i != n1.end(); ++i)
        {
            if (*i>0)
            {
                n_p++;
            }
            else if (*i<0)
            {
                n_n++;
            }
            total=total+*i;
        }
        av=(float)total/i;
        cout<<"Number of positive integers : "<<n_p<<endl<<"Number of negative integers : "<<n_n<<endl<<"Total : "<<total<<endl<<"Average : "<<av;
    }
}