#include <stdio.h>
#include <iostream>
using namespace std;
int main()
{
	int n;
	0 <= n <= 25;
	cin >> n;
	if (n>=0 && n<=3)
	{
		cout<<"infant";
	}
    else if (n>=4 && n<=12)
    {
    	cout<<"child";

    }
    else if (n>=13 && n<=18)
    {
    	cout<<"youngster";
    }
    else if (n>=19 && n<=25)
    {
    	cout<<"youth";
    }

}