grams = {}
    for line in f:
        gram, year, n, books = line.split()

        grams[gram] = grams.setdefault(gram, 0) + int(n)

    largest_n = 0
    largest_gram = None
    for gram in grams:
        if grams[gram] > largest_n:
            largest_n = grams[gram]
            largest_gram = gram