def main():
    pokemon = open("pokemon.txt").readlines()
    evolutions = open("evolutions.txt").readlines()
    inngrader = {}
    naboer = {}

    for p in pokemon:
        navn = p.strip()
        inngrader[navn] = 0
        naboer[navn] = []
    
    for e in evolutions:
        kobling = e.rstrip().split()
        naboer[kobling[0]].append(kobling[1])
        inngrader[kobling[1]] += 1

    stack = []
    output = []
    for p, i in inngrader.items():
        if i == 0:
            stack.insert(0, p)
    while len(stack) > 0:
        poke = stack.pop(0)
        output.append(poke)
        for ut in naboer[poke]:
            inngrader[ut] -= 1
            if inngrader[ut] == 0:
                stack.insert(0, ut)
    if len(output) < len(inngrader):
        print("Grafen inneholder en sykel, den kan derfor ikke topologisk sorteres.")
    else:
        print(output)

main()