#include<bits/stdc++.h>
using namespace std;
int main(){
  int n;
  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";
  }
  return 0;
}