I don't understand what's wrong with my code

#include <iostream>

using namespace std;

int main()
{
    int n,i,mark;
    double t,coun;
    coun=0.0;
    cin >> n;
    for (i=0; i<n; i++)
    {
        cin >> mark;
        if (mark==3) t=0;
        coun+=mark;
    }

    if (t)  {t=coun/n;}

    if (!t) { cout << "None";}

    if (t == 5)
    {
        cout << "Named";
    }
    else if (t >= 4.5)
    {
        cout << "High";
    }
    else if (t != 0)
    {
        cout << "Common";
    }

    return 0;
}