#include <iostream>
#include <cctype>
#include <string>
#include <cstdio>
#include <sstream>
using namespace std;
bool judge(string s)
{
    int count = 0;
    int dot;
    if (!isdigit(s[0]) && s[0] != ‘-‘)
    {
        return false;
    }
    for (int i = 1; i < s.size(); i++)
    {
        if (!isdigit(s[i]) && s[i] != ‘.‘)
            return false;
        if (s[i] == ‘.‘)
        {
            count++;
            dot = i;
            if (count == 2)
                return false;
            if (s.size() - dot > 3)
                return false;
        }
            

    }
    return true;
}
bool judge2(string s)
{
    try {
        double a;
        //    int h;
        char c[50];
        char ss[50];
        int i = 0;
        for (; i < s.size(); i++)
        {
            ss[i] = s[i];
        }
        ss[i] = s[i];
        //strcpy(ss, s.c_str());
        sscanf(ss, "%lf", &a);
        string b;
        sprintf(c, "%.2lf", a);
        printf("add: a %d", &a);
        printf("addd: c  %d\n", c);
        printf("\nc: %s\n", c);
        //cout << &c[0] << "add:c" << endl;
        //cout << ss << "add : ss" << endl;
        for (int i = 0; i < s.size(); i++)
        {
            if (ss[i] != c[i])
                return false;
        }
        return true;
    }
    catch (...)
    {
        return false;
    }
}
int main()
{
    int N;
    cin >> N;
    string s;
    int cnt = 0;
    int cnt2 = 0;
    double sum = 0;
    //cout << "a";
    for (int i = 0; i < N; i++)
    {
        cin >> s;
        if (!judge2(s))
        {
            cnt++;
            cout << "ERROR: " << s << " is not a legal number" << endl;
        }
        else
        {
            double a = 0;
            
            sscanf(s.c_str(), "%lf", &a);
            //while (1);
            if (a > 1000 || a < -1000)
            {
                cout << "ERROR: " << s << " is not a legal number" << endl;
            }
            else
            {
                cnt2++;
                sum += a;
            }
        }
    }
    //cout << "b";
    if (cnt2 == 0) {
        cout << "The average of 0 numbers is Undefined";
    }
    else if(cnt2>1)
    {
        cout << "The average of " << cnt2 << " numbers is ";
        printf("%.2lf", sum / cnt2);
    }
    else if(cnt2 == 1)
    {
        printf("The average of 1 number is %.2lf", sum);
    }
    return 0;
}