#include<stdio.h>
int main()
{
    int n;
    0<=n<=25;
    scanf("%d",&n);
    if(0<=n&&n<=3)
    printf("infant");
    else if(4<=n&&n<=12)
    printf("child");
    else if(13<=n&&n<=18)
    printf("youngster");
    else if(19<=n&&n<=25)
    printf("youth");
    return 0;
}