#include<stdio.h> int main() { int n;

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

}