#Primary U.S. interstate highways are numbered 1-99. 
#Odd numbers (like the 5 or 95) go north/south, 
#and evens (like the 10 or 90) go east/west. 
#Auxiliary highways are numbered 100-999, 
#and service the primary highway indicated by the rightmost two digits. 
#Thus, I-405 services I-5, and I-290 services I-90. 
#Note: 200 is not a valid auxiliary highway because 00 is not a valid primary highway number.

#Given a highway number, 
#indicate whether it is a primary or auxiliary highway. 
#If auxiliary, indicate what primary highway it serves. 
#Also indicate if the (primary) highway runs north/south or east/west.

highway_number = int(input())

# primary U.S. Interstate highways 1-99 
if 1 <= highway_number <= 99: 
    if highway_number % 2 == 0: 
        direction = "east/west"
    else:
        direction = "north/south"

    print(f"I-{highway_number} is primary, going {direction}.")

# Auxiliary highways 100-99 
elif 100 <= highway_number <= 99: 
    rightmost = highway_number % 100 

    if rightmost == 0: 
        print(f"{highway_number} is not a valid interstate highway number.")
    else: 
        if rightmost % 2 == 0:
            direction = "east/west"
        else: 
            direction = "north/south"

        print(f" I-{highway_number} is auxiliary, serving I-{rightmost}, going {direction}.")

else: 
    print(f"{highway_number} is not a valid interstate highway number.")