/*
 * Primary interstate highway numbers are 1-99
 * Odds go north/south
 * evens go east/west
 *
 * Aux highways are 100-999
 * Right most two digest are the primary highway it services
 *
 * givein a highway number, indicate primary or aux
 * if aux indicate which highway it serves
 *
 * Also indicate if the primary highway runs north/south
 * or east/west
 *
 * input: 90
 * output: I-90 is primary, going east/west.
 *
 * input: 290
 * output: I-290 is auxiliary, serving I-90, going east/west.
 *
 * input: 0
 * output: 0 is not a valid interstate highway number.
 */

#include <iostream>
using namespace std;

int main() {
   int highwayNumber;
   string highwayDirection;


   cin >> highwayNumber;

   /* Type your code here. */

   if (highwayNumber % 2 == 0){
	   highwayDirection="east/west";
   }
   else{
	   highwayDirection="north/south";
   }

   if ((highwayNumber < 1) ||
		(highwayNumber > 999)){
	   cout << highwayNumber << " is not a valid interstate highway number.\n";
   }
   //Primary
   else if (highwayNumber < 100){
	   cout << "I-" << highwayNumber << " is primary, going " <<
		   highwayDirection << ".\n";
	//Aux
   }
   else{
	   cout << "I-" << highwayNumber << " is auxiliary, serving I-"<<
		   highwayNumber%100 << ", going " << highwayDirection << ".\n";
   }



   return 0;
}